This is the specification of the Platform for Privacy Preferences 1.1 (P3P 1.1). This document, along with its normative references, includes all the specification necessary for the implementation of interoperable P3P 1.1 applications. P3P 1.1 is based on the P3P 1.0 Recommendation and adds some features using the P3P 1.0 Extension mechanism. It also contains a new binding mechanism that can be used to bind policies for XML Applications beyond HTTP transactions.

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

This is a Public Working Draft of the P3P 1.1 Specification for review by W3C Members and other interested parties. P3P 1.1 was developed from suggestions out of a Workshop in Dulles/Virginia and a Workshop in Kiel/Germany. The community at large gave feedback on limitations and shortcomings of P3P 1.0. As far as those suggestions have found sufficient support, they are now included in this new P3P 1.1 Working Draft. All new features are built using P3P's own Extension mechanism. Those extensions are contained in a new XML Schema in Appendix 5 and carry their own new namespace. All P3P 1.0 preserve their old namespace. Additionally, this Working Draft contains all the errata to P3P 1.0. Note that all changes from the P3P 1.0 Recommendation to this Working Draft are marked up with a different background color, even in the outline.

Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

Patent disclosures relevant to this specification may be found on the P3P1.1 patent disclosure page, in conformance with W3C policy.

1. Introduction

The Platform for Privacy Preferences Project (P3P) enables Web sites to express their privacy practices in a standard format that can be retrieved automatically and interpreted easily by user agents. P3P user agents will allow users to be informed of site practices (in both machine- and human-readable formats) and to automate decision-making based on these practices when appropriate. Thus users need not read the privacy policies at every site they visit.

Although P3P provides a technical mechanism for ensuring that users can be informed about privacy policies before they release personal information, it does not provide a technical mechanism for making sure sites act according to their policies. Products implementing this specification MAY provide some assistance in that regard, but that is up to specific implementations and outside the scope of this specification. However, P3P is complementary to laws and self-regulatory programs that can provide enforcement mechanisms. In addition, P3P does not include mechanisms for transferring data or for securing personal data in transit or storage. P3P may be built into tools designed to facilitate data transfer. These tools should include appropriate security safeguards.

1.1 The P3P 1.1 Specification

The P3P1.1 specification defines the syntax and semantics of P3P privacy policies, and the mechanisms for associating policies with Web resources. P3P policies consist of statements made using the P3P vocabulary for expressing privacy practices. P3P policies also reference elements of the P3P base data schema -- a standard set of data elements that all P3P user agents should be aware of. The P3P specification includes a mechanism for defining new data elements and data sets, and a simple mechanism that allows for extensions to the P3P vocabulary.

1.1.1 Goals and Capabilities of P3P 1.1

P3P version 1.0 is a protocol designed to inform Web users about the data-collection practices of Web sites. It provides a way for a Web site to encode its data-collection and data-use practices in a machine-readable XML format known as a P3P policy. The P3P specification defines:

A standard schema for data a Web site may wish to collect, known as the "P3P base data schema" (5.5)
A standard set of uses, recipients, data categories, and other privacy disclosures
An XML format for expressing a privacy policy
A means of associating privacy policies with Web pages or sites, and cookies
A mechanism for transporting P3P policies over HTTP

The goal of P3P is twofold. First, it allows Web sites to present their data-collection practices in a standardized, machine-readable, easy-to-locate manner. Second, it enables Web users to understand what data will be collected by sites they visit, how that data will be used, and what data/uses they may "opt-out" of or "opt-in" to.

A number of changes were made in P3P version 1.1. These are enumerated in the changelog at the end of this document. The most significant changes are summarized here:

All the errata from P3P 1.0 have been incorporated into this specification.
In Section 1.3, definitions are now provided for identified, identifiable, linked, and linkable data
In Section 2.3.2.9 an optional OUR-HOST element has been added for declaring domain relationships, allowing user agents to recognize when hosts in different domains are owned by the same entity or entities acting as agents for one another.
In Section 2.5 a new P3P generic attribute for XML applications has been added. This is a new mechanism for binding P3P policies to XML elements that describe interfaces, for example, in XForms or WSDL.
In Section 3.2.3 and Section 3.3.2 a mechanism has been added for naming P3P STATEMENT elements and grouping STATEMENT elements together. This allows user agents to better organize the summary display of P3P policies.
In Section 3.2.7 and Section 3.2.8 new definitions are provided for the DISPUTES and REMEDIES elements and their sub-elements.
In Section 3.36 a new definition is provided for the RECIPIENT element.
In Section 3.4 a new definition is provided for the demographic element.
In Section 3.3.5.1 an optional ppurpose element has been added added to allow user agents to determine the primary reason why the data recipient is collecting data.
In Section 3.3.6.1 an optional JURSIDICTION element has been added for declaring the jurisdiction of data recipients.
In Section 4 language was added to explain the use of compact policies as a performance optimization, and to emphasize their optional nature and non-authoritative status.
In Section 4.2.10 new syntax has been added to provide a compact version of the STATEMENT element for use in compact policies. This allows for the creation of compact policies that make more granular statements about data practices than is possible with the P3P 1.0 syntax.
In Section 5, the format for specifying P3P data schemas has been changed substantially so that it is now simpler and more standardized than the format used in P3P 1.0. The new format uses the XML Schema Definition Standard (XSD) format, which can be validated against an XML schema. In Appendix 3 the P3P base data schema definition has been updated to reflect this change.
In Section 6 new user agent guidelines have been added to assist user agent implementers. These guidelines include a set of plain language translations of P3P vocabulary elements.
The XML DTD definition for P3P has been removed from the Specification.

1.1.2 Example of P3P in Use

As an introduction to P3P, let us consider one common scenario that makes use of P3P. Claudia has decided to check out a store called CatalogExample, located at http://www.catalog.example.com/. Let us assume that CatalogExample has placed P3P policies on all their pages, and that Claudia is using a Web browser with P3P built in.

Claudia types the address for CatalogExample into her Web browser. Her browser is able to automatically fetch the P3P policy for that page. The policy states that the only data the site collects on its home page is the data found in standard HTTP access logs. Now Claudia's Web browser checks this policy against the preferences Claudia has given it. Is this policy acceptable to her, or should she be notified? Let's assume that Claudia has told her browser that this is acceptable. In this case, the homepage is displayed normally, with no pop-up messages appearing. Perhaps her browser displays a small icon somewhere along the edge of its window to tell her that a privacy policy was given by the site, and that it matched her preferences.

Next, Claudia clicks on a link to the site's online catalog. The catalog section of the site has some more complex software behind it. This software uses cookies to implement a "shopping cart" feature. Since more information is being gathered in this section of the Web site, the Web server provides a separate P3P policy to cover this section of the site. Again, let's assume that this policy matches Claudia's preferences, so she gets no pop-up messages. Claudia continues and selects a few items she wishes to purchase. Then she proceeds to the checkout page.

The checkout page of CatalogExample requires some additional information: Claudia's name, address, credit card number, and telephone number. Another P3P policy is available that describes the data that is collected here and states that her data will be used only for completing the current transaction, her order.

Claudia's browser examines this P3P policy. Imagine that Claudia has told her browser that she wants to be warned whenever a site asks for her telephone number. In this case, the browser will pop up a message saying that this Web site is asking for her telephone number, and explaining the contents of the P3P statement. Claudia can then decide if this is acceptable to her. If it is acceptable, she can continue with her order; otherwise she can cancel the transaction.

Alternatively, Claudia could have told her browser that she wanted to be warned only if a site is asking for her telephone number and was going to give it to third parties and/or use it for uses other than completing the current transaction. In that case, she would have received no prompts from her browser at all, and she could proceed with completing her order.

Note that this scenario describes one hypothetical implementation of P3P. Other types of user interfaces are also possible.

1.1.3 P3P Policies

P3P policies use an XML with namespaces (cf. [XML] and [XML-Name]) encoding of the P3P vocabulary to provide contact information for the legal entity making the representation of privacy practices in a policy, enumerate the types of data or data elements collected, and explain how the data will be used. In addition, policies identify the data recipients, and make a variety of other disclosures including information about dispute resolution, and the address of a site's human-readable privacy policy. P3P policies must cover all relevant data elements and practices. However, legal issues regarding law enforcement demands for information are not addressed by this specification. It is possible that a site that otherwise abides by its policy of not redistributing data to others may be required to do so by force of law. P3P declarations are positive, meaning that sites state what they do, rather than what they do not do. The P3P vocabulary is designed to be descriptive of a site's practices rather than simply an indicator of compliance with a particular law or code of conduct. However, user agents may be developed that can test whether a site's practices are compliant with a law or code.

P3P policies represent the practices of the site. Intermediaries such as telecommunication providers, Internet service providers, proxies and others may be privy to the exchange of data between a site and a user, but their practices may not be governed by the site's policies. In addition, note that each P3P policy is applied to specific Web resources (Web pages, images, cookies, etc.) listed in a policy reference file. By placing one or more P3P policies on a Web site, a company or organization does not make any statements about the privacy practices associated with other Web resources not mentioned in their policy reference file, with other online activities that do not involve data collected on Web sites covered by their P3P policy, or with offline activities that do not involve data collected on Web sites covered by their P3P policy.

In cases where the P3P vocabulary is not precise enough to describe a Web site's practices, sites should use the vocabulary terms that most closely match their practices and provide further explanations (as stated in Section 3.2). However, policies MUST NOT make false or misleading statements.

1.1.4 P3P User Agents

P3P 1.1 user agents can be built into Web browsers, browser plug-ins, or proxy servers. They can also be implemented as Java applets or JavaScript; or built into electronic wallets, automatic form-fillers, or other user data management tools. P3P user agents look for references to a P3P policy at a well-known location, in P3P headers in HTTP responses, and in P3P link tags embedded in HTML content. These references indicate the location of a relevant P3P policy. User agents can fetch the policy from the indicated location, parse it, and display symbols, play sounds, or generate user prompts that reflect a site's P3P privacy practices. They can also compare P3P policies with privacy preferences set by the user and take appropriate actions. P3P can perform a sort of "gate keeper" function for data transfer mechanisms such as electronic wallets and automatic form fillers. A P3P user agent integrated into one of these mechanisms would retrieve P3P policies, compare them with user's preferences, and authorize the release of data only if a) the policy is consistent with the user's preferences and b) the requested data transfer is consistent with the policy. If one of these conditions is not met, the user might be informed of the discrepancy and given an opportunity to authorize the data release themselves.

The P3P 1.1 Specification gives implementers a lot of flexibility to determine the design and functionality of P3P user agents. However, the specification does include some requirements and guidelines for user agent implementers. Most of these can be found in section 6 and Appendix 7.

1.1.5 Implementing P3P 1.1 on Servers

Web sites can implement P3P 1.1 on their servers by translating their human-readable privacy policies into P3P syntax and then publishing the resulting files along with a policy reference file that indicates the parts of the site to which the policy applies. Automated tools can assist site operators in performing this translation. P3P 1.1 can be implemented on existing HTTP/1.1-compliant Web servers without requiring additional or upgraded software. Servers may publish their policy reference files at a well-known location, or they may reference their P3P policy reference files in HTML/XHTML content using a link tag. Alternatively, compatible servers may be configured to insert a P3P extension header into all HTTP responses that indicates the location of a site's P3P policy reference file.

Web sites have some flexibility in how they use P3P: they can opt for one P3P policy for their entire site or they can designate different policies for different parts of their sites. A P3P policy MUST cover all data generated or exchanged as part of a site's HTTP interactions with visitors. In addition, some sites may wish to write policies that cover all data an entity collects, regardless of how the data is collected.

1.1.6 Future Versions of P3P

Significant sections were removed from earlier drafts of the P3P 1.0 specification in order to facilitate rapid implementation and deployment of a P3P first step. A future version of the P3P specification might incorporate those features after P3P 1.0 is deployed. Such specification would likely include improvements based on feedback from implementation and deployment experience as well as four major components that were part of the original P3P vision but not included in P3P 1.0 or 1.1:

1.1.7 Backwards Compatibility

P3P 1.1 has been designed so that P3P 1.0 user agents can process P3P 1.1 policies and policy reference files. This implies both that the P3P 1.1 policies and policy reference files are fully compliant with the P3P 1.0 XML schema, and that the semantics of these files will not be misinterpreted by a user agent that interprets them according to the P3P 1.0 specification. All new syntax introduced in P3P 1.1 has been introduced as optional extensions using the P3P 1.0 extension mechanism. Changes to requirements or definitions introduced in P3P 1.1 add clarity where the P3P 1.0 specification is ambiguous, but do not cause a particular P3P vocabulary element to have different meanings in P3P 1.0 and P3P 1.1. In addition, some new requirements or features have been introduced in the P3P 1.1 specification that do not impact the ability of P3P 1.0 user agents to process P3P 1.1 policies and policy reference files. For the base data-schema, the guidelines described there apply.

Note, P3P 1.1 data schemas cannot be read by P3P 1.0 user agents. This only impacts P3P 1.0 user agents that download and parse data schemas, and only when they access P3P 1.1 web sites that make use of data schemas beyond the P3P base data schema.

1.2 About this Specification

This document, along with its normative references, includes all the specification necessary for the implementation of interoperable P3P applications.

The following key words are used throughout the document and have to be read as interoperability requirements. This specification uses words as defined in RFC2119 [KEY] for defining the significance of each particular requirement. These words are:

The P3P specification defines, with the exception of section 2.2.2, section 2.2.3 and section 4, an XML with namespaces syntax (cf. [XML] and [XML-Name]). In the following, for the sake of brevity we will liberally talk about "XML", meaning the more accurate "XML with namespaces".

A BNF-like notation is also used thorough the specification: the [ABNF] notation used in this specification is specified in RFC2234 and summarized in Appendix 6. However, note that in the case of XML syntax, such ABNF syntax is only a grammar representative used to enhance readability (lacking, for example, all the syntactic flexibilities that are implicitly included in XML, e.g. whitespace rules, quoting using either single quote (') or double quote ("), character escaping, comments, case sensitivity, order of attributes, namespace handling), and as such it has no normative value. All the XML syntax defined in this specification MUST conform to the XML Schema for P3P (see Appendix 4), which, together with the other constraints expressed in this specification using natural language, constitutes the normative definition.

The (non-normative) DTD provided formerly in Appendix 5 was removed due to the limits of expressiveness. The XML Schema is now the only normative source.

As far as the non-XML syntax defined in this specification is concerned (section 2.2.2 defining P3P's HTTP header, section 2.2.3 defining usage of P3P in HTML, and section 4 defining compact policies), instead, the ABNF notation (together with the other constraints expressed in this specification using natural language) constitutes the normative definition.

1.3 Identity Definitions in the P3P Specification

In privacy regulations, guidelines and papers about privacy a variety of terms are used to describe data that identifies an individual to varying degrees.

The European Union Directive defines an identifiable person as one who can be identified, directly or indirectly, in particular by reference to an identification number or to one or more factors specific to his physical, physiological, mental, economic, cultural or social identity. The Directive also states that in determining whether a person is identifiable account should be taken of all the means likely reasonably to be used either by the controller or by any other person to identify the said person; whereas the principles of protection shall not apply to data rendered anonymous in such a way that the data subject is no longer identifiable.

In Australia, personal information is information about an individual who can be identified, or whose identity could be reasonably ascertained. In Canada personal information means information about an identifiable individual. In the United States, different sectors have different standards for identifiability of data. Similarly, in many other policy documents, terms such as personally identifiable information (PII) are often not defined or the cause for heated debate.

The P3P Specification Working Group has taken the view point that most information referring to an individual is identifiable in some way. As with other important areas of the specification, the goal of the working group was to allow for a wide variety of understandings of identity in order to allow data collectors to best express their policy and users to make choices based on a definition of identity information that is important to them. (More information on the debate and the definitions can be found in [Cranor,P3P].

1.3.1 Identified Data

The most common term in the specification is identified data and focuses on whether a service knows the data subject's identity.

Identified data is information in a record or profile that can reasonably be tied to an individual. Admittedly, this is a somewhat subjective standard. For example, a data collector storing Internet Protocol (IP) addresses (which can be created dynamically or could be static and therefore tied to a particular computer used by a single individual) should consider the IP address identified data only when this data is added to the record or profile of a specific individual. In the more common case, where data collectors use IP addressing information in the aggregate or make no attempt to tie the IP address to a specified individual or computer over a long period of time, IP addresses are not considered identified even though it is possible for someone (eg, law enforcement agents with proper subpoena powers) to identify the individual based on the stored data.

As mentioned above, in the P3P context, any data that can be used reasonably by a data controller or any other person to identify an individual is considered to be identifiable data. The P3P specification uses the term identified to describe a subset of this data that can be reasonably be used by a data collector without assistance from other parties to identify an individual.

1.3.2 Non-Identifiable Data

The working group also felt that data collectors should be able acknowledge when they make specific attempts to anonymize information.

The term non-identifiable data refers to efforts made specifically to de-identify data. For example, a data collector collecting and storing IP addresses but not using them should NOT call this data non-identifiable even in the common case where they have no plans to identify an actual individual or computer. However, if a Web site collects IP addresses, but actively deletes all but the last four digits of this information in order to determine short term use, but insure that a particular individual or computer cannot be consistently identified, then the data collector can and should call this information non-identifiable. Also, non-identifiable can be used in cases where no information is being collected at all. Since most Web servers are designed to keep Web logs for maintenance, this would most likely mean that the data collector has taken specific efforts to ensure the anonymity of users.

Under the above definitions, a lot of information could be identifiable (not specifically made anonymous), but not identified (reasonably able to be tied to an individual or computer).

1.3.3 Identifiers

The Working Group decided against an identified or identifiable label for particular types of data. However, user agent implementers have the option of assigning these or other labels themselves and building user interfaces that allow users to make decisions about web sites on the basis of how they collect and use certain types of data.

The Working Group felt that different user agent implementations could be created to focus on different concerns around data type. Therefore, the working group enabled the creation of a robust data schema including broad categories of information that may be considered sensitive by certain user groups. The Working Group hopes that a diverse set of user agents will be created to allow users the ability to make identity decisions based on specific collections and types of collects if they desire to do so. For example, a user agent could allow users to opt to be prompted when medical or financial identifier is being collected, independent of how that information is being used.

1.3.4. Linked and Linkable Data

Cookies often store a unique number or database key that links to a database record, rather than storing the complete database record. Web sites that use P3P must disclose not only the types of data stored directly in a cookie, but also all data linked to a cookie. A large amount of data may be "linkable" to a cookie without actually being "linked" to that cookie.

A piece of data X is said to be linkable to a cookie Y if a key stored in cookie Y can be used to retrieve X either directly or indirectly. A direct retrieval might happen, for example, if the key is associated with a database record in which X is stored. An indirect retrieval might happen, for example, if the key is associated with a database record that contains a piece of data that may be used, in turn, as a key to retrieve a record in a second database, and X is stored in the second database. Furthermore, if cookie Y is stored in a server log file, the log file may facilitate further linking. For example, when cookie Y is replayed, it may be accompanied by a referer field that includes additional identifiable information or even another key. Alternatively, imagine a web site that sets two cookies, Y and Z. Cookies Y and Z may get replayed in the same HTTP request and subsequently recorded side-by-side in the server log file. Thus all data associated with cookie Y are also linkable to cookie Z. Indeed, unless precautions are taken to minimize server log files and severely restrict the use of identifiable data, almost all data an entity stores about an individual are likely to be linkable to any cookies they have set on that individual's computer.

A piece of data X is said to be linked to a cookie Y if at least one of the following activities may take place as a result of cookie Y being replayed, immediately upon cookie replay or at some future time (perhaps as a result of retrospective analysis or processing of server logs):

Entities should consider their data collection and storage architectures carefully to determine what data may be linkable to their cookies and what data will actually be linked to each cookie. If data is linkable but not linked to a particular cookie, it does not have to be disclosed in a P3P statement concerning that cookie. However, should the entity associated with that P3P policy ever link the data for any reason other than to comply with law enforcement demands, they would be in violation of their stated policy.

1.4 Terminology

2. Referencing Policies

2.1 Overview and Purpose of Policy References

Locating a P3P policy is one of the first steps in the operation of the P3P protocol. Services use policy references to state what policy applies to a specific URI or set of URIs. User agents use policy references to locate the privacy policy that applies to a Web resource, so that they can process that policy for the benefit of their user.

Policy references are used extensively as a performance optimization. P3P policies are typically several kilobytes of data, while a URI that references a privacy policy is typically less than 100 bytes. In addition to the bandwidth savings, policy references also reduce the need for computation: policies can be uniquely associated with URIs, so that a user agent need only parse and process a policy once rather than process it with every document to which the policy applies. Furthermore, by placing the information about relevant policies in a centralized location, Web site administration is simplified.

A policy reference file is used to associate P3P policies with certain regions of URI-space. The policy reference file is an XML with namespaces (see [XML] and [XML-Name]) file that can specify the policy for a single Web document, portions of a Web site, or for an entire site. The policy reference file may refer to one or more P3P policies; this allows for a single reference file to cover an entire site, even if different P3P policies apply to different portions of the site.The policy reference file is used to make any or all of the following statements:

2.2 Locating Policy Reference Files

This section describes the mechanisms used to indicate the location of a policy reference file. Detailed syntax is also given for the supported mechanisms.

The location of the policy reference file can be indicated using one of four mechanisms. The policy reference file

Note that if user agents support retrieving HTML (resp. XHTML) content over HTTP, they MUST handle mechanisms 1, 2 and 3 (resp. 4) listed above interchangeably. See also the requirements for non-ambiguity.

Policies are applied at the level of resources. A "page" from the user's perspective may be composed of multiple HTTP resources; each may have its own P3P policy associated with it. As a practical note, however, placing many different P3P policies on different resources on a single page may make rendering the page and informing the user of the relevant policies difficult for user agents. Additionally, services are recommended to attempt to craft their policy reference files such that a single policy reference file covers any given "page"; this will speed up the user's browsing experience.

For a user agent to process the policy that applies to a given resource, it must locate the policy reference file for that resource, fetch the policy reference file, parse the policy reference file, fetch any required P3P policies, and then parse the P3P policy or policies.

This document does not specify how P3P policies may be associated with Web resources retrieved by means other than HTTP. However, it does not preclude future development of mechanisms for associating P3P policies with resources retrieved using other protocols. Furthermore, additional methods of associating P3P policies with HTTP resources may be developed in the future.

2.2.1 Well-Known Location

Web sites using P3P MAY (and, are strongly encouraged to) place a policy reference file in a "well-known" location. To do this, a policy reference file would be made available on the site at the path /w3c/p3p.xml.

Note that sites are not required to use this mechanism; however, by using this mechanism, sites can ensure that their P3P policy will be accessible to user agents before any other resources are requested from the site. This will reduce the need for user agents to access the site using safe zone practices. Additionally, if a site chooses to use this mechanism, the policy reference file located in the well-known location is not required to cover the entire site. For example, sites where not all of the content is under the control of a single organization MAY choose not to use this mechanism, or MAY choose to post a policy reference file which covers only a limited portion of the site.

Use of the well-known location for a policy reference file does not preclude use of other mechanisms for specifying a policy reference file. Portions of the site MAY use any of the other supported mechanisms to specify a policy reference file, so long as the non-ambiguity requirements are met.

For example, imagine a shopping-mall Web site run by the MallExample company. On their Web site (mall.example.com), companies offering goods or services at the mall would get a company-specific subtree of the site, perhaps in the path /companies/company-name. The MallExample company may choose to put a policy reference file in the well-known location which covers all of their site except the /companies subtree. Then if the ShoeStoreExample company has some content in /companies/shoestoreexample, they could use one of the other mechanisms to indicate the location of a policy reference file covering their portion of the mall.example.com site.

One case where using the well-known location for policy reference files is expected to be particularly useful is in the case of a site which has divided its content across several hosts. For example, consider a site which uses a different logical host for all of its Web-based applications than for its static HTML content. The other mechanisms allowed for specifying the location of a policy reference file require that some URI on the host being accessed must be fetched to locate the policy reference file. However, the well-known location mechanism has no such requirement. Consider the example of an HTML form located on www.example.com. Imagine that the action URI on that form points to server cgi.example.com. The policy reference file that covers the form is unable to make any statements about the action URI that processes the form. However, the site administrator publishes a policy reference file at http://cgi.example.com/w3c/p3p.xml that covers the action URI, thus enabling a user agent to easily locate the P3P policy that applies to the action URI before submitting the form contents.

2.2.2 HTTP Headers

Any document retrieved by HTTP MAY point to a policy reference file through the use of a new response header, the P3P header ([P3P-HEADER]). If a site is using P3P headers, it SHOULD include this on responses for all appropriate request methods, including HEAD and OPTIONS requests.

The P3P header gives one or more comma-separated directives. The syntax follows:

In keeping with the rules for other HTTP headers, the name of the P3P header may be written with any casing. The contents should be specified using the casing precisely as specified in this document.

The policyref directive gives a URI which specifies the location of a policy reference file which may reference the P3P policy covering the document that pointed to the reference file, and possibly others as well. When the policyref attribute is a relative URI, that URI is interpreted relative to the request URI. Note that fetching the URI given in the policyref directive MAY result in a 300-class HTTP return code (redirection); user agents MUST interpret those redirects with normal HTTP semantics. Services should note, of course, that use of redirects will increase the time required for user agents to find and interpret their policies. The policyref URI MUST NOT be used for any other purpose beyond locating and referencing P3P policies.

The compact-policy-field is used to specify "compact policies". This is described in Section 4.

User agents which find unrecognized directives (in the extension-fields) MUST ignore the unrecognized directives. This is to allow easier deployment of future versions of P3P.

2. Server returns content and the P3P header pointing to the policy of the resource.

2.2.3 The HTML link Tag

Servers MAY serve HTML content with embedded link tags (cf. [HTML]) that indicate the location of the relevant P3P policy reference file. This use of P3P does not require any change in the server behavior.

The link tag encodes the policy reference information that could be expressed using the P3P header. The link tag takes the following form (here, we just produce one possible ABNF format for the link tag, and suppose the [HTML] syntax rules can be used when using such a tag into an HTML file):

When the href attribute is a relative URI, that URI is interpreted relative to the request URI.

In order to illustrate with an example the use of the link tag, we consider the policy reference expressed in Example 2.1 using HTTP headers. That example can be equivalently expressed using the link tag with the following piece of HTML:

Finally, note that since the p3p-link-tag is embedded in an HTML document, its character encoding will be the same as that of the HTML document. In contrast to P3P policy and policy reference documents (see section 2.3 and section 3 below), the p3p-link-tag need not be encoded using [UTF-8]. Note also that the link tag is not case sensitive.

2.2.4 The XHTML link tag

Correspondingly to the HTML link tag, P3P also supports XHTML (cf. [XHTML-MOD]). Servers MAY serve XHTML content that, using the XHTML Link Module (cf. Section 5.19 of [XHTML-MOD]), indicates the location of the relevant P3P policy reference file with an embedded XHTML link tag. Like in the HTML case, an XHTML link tag can be used to encode the policy reference information that could be expressed using the P3P header, by:

2.2.5 HTTP ports and other protocols

The mechanisms described here MAY be used for HTTP transactions over any underlying protocol. This includes plain-text HTTP over TCP/IP connections or encrypted HTTP over SSL connections, as well as HTTP over any other communications protocol designers wish to implement.

URIs MAY contain network port numbers, as specified in RFC 2396 [URI]. For the purposes of P3P, different ports on a single host MUST be considered to be separate "sites". Thus, for example, the policy reference file at the well-known location for www.example.com on port 80 (http://www.example.com/w3c/p3p.xml) would not give any information about the policies which apply to www.example.com when accessed over SSL (as the SSL communication would take place on a different port, 443 by default).

This document does not specify how P3P policies may be associated with resources retrieved by means other than HTTP. However, it does not preclude future development of mechanisms for associating P3P policies with resources retrieved over other protocols. Furthermore, additional methods of associating P3P policies with resources retrieved using HTTP may be developed in the future.

2.3 Policy Reference File Syntax and Semantics

2.3.1 Example Policy Reference File

Note this example also includes via EXPIRY a relative expiry time in the document (cf. Section 2.3.2.3.2).

2.3.2 Policy Reference File Definition

This section defines the syntax and semantics of P3P policy reference files. All policy reference files MUST be encoded using [UTF-8]. P3P servers MUST encode their policy reference files using this syntax.

2.3.2.1 Policy reference file processing

2.3.2.1.1 Significance of order

A policy reference file has the META element as root. It may contain multiple POLICY-REF elements. If it does contain more than one element, they MUST be processed by user agents in the order given in the file. When a user agent is attempting to determine what policy applies to a given URI, it MUST use the first POLICY-REF element in the policy reference file which applies to that URI.

Note that each POLICY-REF may contain multiple INCLUDE, EXCLUDE, METHOD, COOKIE-INCLUDE, and COOKIE-EXCLUDE elements and that all of these elements within a given POLICY-REF MUST be considered together to determine whether the POLICY-REF applies to a given URI. Thus, it is not sufficient to find an INCLUDE element that matches a given URI, as EXCLUDE or METHOD elements may serve as modifiers that cause the POLICY-REF not to match.

2.3.2.1.2 Wildcards in policy reference files

Policy reference files make statements about what policy applies to a given URI. Policy reference files support a simple wildcard character to allow making statements about regions of URI-space. The character asterisk ('*') is used to represent a sequence of 0 or more of any character. No other special characters (such as those found in regular expressions) are supported.

Note that since the asterisk is also a legal character in URIs ([URI]), some special conventions have to be followed when encoding such "extended URIs" in a policy reference file:

URI escaping and unescaping is very much dependant on the actual scheme used, and might even differ between individual components within a single scheme, so no simple rule for which characters need to be escaped can be given here. Please refer directly to [URI] for details on the standard escaping process. Note that P3P user agents MAY ignore any URI pattern that does not conform to [URI].

The wildcard character MAY be used in the INCLUDE and EXCLUDE elements, in the COOKIE-INCLUDE and COOKIE-EXCLUDE elements, and in the HINT element.

2.3.2.2 The META and POLICY-REFERENCES elements

2.3.2.3 Policy reference file lifetimes and the EXPIRY element

2.3.2.3.1 Motivation and mechanism

It is desirable for servers to inform user agents about how long they can use the claims made in a policy reference file. By enabling clients to cache the contents of a policy reference file, it reduces the time required to process the privacy policy associated with a Web resource. This also reduces load on the network. In addition, clients that don't have a valid policy reference file for a URI will need to use "safe zone" practices for their requests. If clients have policy reference files that they know are still valid, then they can make more informed decisions on how to proceed.

In order to achieve these benefits, policy reference files SHOULD contain an EXPIRY element, which indicates the lifetime of the policy reference file. If the policy reference file does not contain an EXPIRY element, then it defaults to 24-hour lifetime.

The lifetime of a policy reference file tells user agents how long they can rely on the claims made in the policy reference file. By setting the lifetime of a policy reference file, the publishing site agrees that the policies mentioned in the policy reference file are appropriate for the lifetime of the policy reference file. For example, if a policy reference file has a lifetime of 3 days, then a user agent need not reload that file for 3 days, and can assume that the references made in that policy reference file are good for 3 days. All of the policy references made in a single policy reference file will receive the same lifetime. The only way to specify different lifetimes for different policy references is to use separate policy reference files.

The same mechanism used to indicate the lifetime of a policy reference file is also used to indicate the lifetime of a P3P policy. Thus P3P POLICIES elements SHOULD have an EXPIRY element associated with them as well. This lifetime applies to all P3P policies contained within that POLICIES element. If there is no EXPIRY element associated with a P3P policy, then it defaults to 24-hour lifetime.

When picking a lifetime for policies and policy reference files, sites need to pick a lifetime which balances two competing concerns. One concern is that the lifetime ought to be long enough to allow user agents to receive significant benefits from caching. The other concern is that the site would like to be able to change their policy for new data collection without waiting for an extremely long lifetime to expire. It is expected that lifetimes in the range of 1-7 days would be a reasonable balance between these two competing desires. Sites also need to remember the policy update requirements when updating their policies.

When a policy reference file has expired, the information in the policy reference file MUST NOT be used by a user agent until that user agent has successfully revalidated the policy reference file, or has fetched a new copy of the policy reference file.

Note that while user agents are not obligated to revalidate policy reference files or policy files that have not expired, they MAY choose to revalidate those files before their expiry period has passed in order to reduce the need for using "safe zone" practices. A valid P3P user agent implementation does not need to contain a cache for policies and policy reference files, though the implementation will have better performance if it does.

2.3.2.3.2 The EXPIRY element

The EXPIRY element can be used in a policy reference file and/or in a POLICIES element to state how long the policy reference file (or policies) remains valid. The expiry is given as either an absolute expiry time, or a relative expiry time. An absolute expiry time is a time, given in GMT, until which the policy reference file (or policies) is valid. A relative expiry time gives a number of seconds for which the policy reference file (or policies) is valid. This expiry time is relative to the time the policy reference file (or policies) was requested or last revalidated by the client. This computation MUST be done using the time of the original request or revalidation, and the current time, with both times generated from the client's clock. Revalidation is defined in section 13.3 of [HTTP1.1].

The minimum amount of time for any relative expiry time is 24 hours, or 86400 seconds. Any relative expiration time shorter than 86400 seconds MUST be treated as being equal to 86400 seconds in a client implementation. If a client encounters an absolute expiration time that is in the past, it MUST act as if NO policy reference file (or policy) is available. See section 2.4.7 "Absence of Policy Reference File" for the required procedure in such cases.

2.3.2.3.3 Requesting Policies and Policy Reference Files

In a real-world network, there may be caches which will cache the contents of policies and policy reference files. This is good for increasing the overall network performance, but may have deleterious effects on the operation of P3P if not used correctly. There are two specific concerns:

HTTP 1.1 [HTTP1.1] contains powerful cache-control mechanisms to allow clients to place requirements on the operations of network caches; these mechanisms can resolve the problems mentioned above. The specific method will be discussed below.

HTTP 1.0, however, does not provide those more sophisticated cache control mechanisms. An HTTP 1.0 caching proxy will, in all likelihood, compute a cache lifetime for the policy reference file (or policies) based on the file's last-modified date; the resulting cache lifetime could be significantly longer than the lifetime specified by the EXPIRY element. The caching proxy could then serve the policy reference file (or policies) to clients beyond the lifetime in the EXPIRY; the result would be that user-agents would receive a useless policy reference file (or policies).

The second problem with an HTTP 1.0 caching proxy is that a user agent has no way to know how long the reference file may have been stored by the caching proxy. If the policy reference file (or policies) relies on relative expiry, it would then be impossible for the user agent to determine if the reference file's lifetime has already expired, or when it will expire.

Thus, if a user agent is requesting a policy reference file or a policy, and does not know for certain that there are no HTTP 1.0 caches in the path to the origin server, then the request MUST force an end-to-end revalidation. This can be done with the Pragma: no-cache HTTP request-header. Note that neither HTTP nor P3P define a way to determine if there is a HTTP 1.0-compliant cache in any given network path, so unless the user agent has this information derived from an outside source, it MUST force the end-to-end revalidation.

If the user agent has some way to know that all caches in the network path to the origin server are compliant with HTTP 1.1 (or that there are no caches in the network path to the origin server), then the client MAY do the following instead of forcing an end-to-end revalidation:

Note that it is impossible for a client to accurately predict the amount of latency that may affect an HTTP request. Thus, if the policy reference file covering a request is going to expire soon, clients MAY wish to consider warning their users and/or revalidating the policy reference file before continuing with the request.

2.3.2.3.4 Error handling for policy reference file and policy lifetimes

2.3.2.4 The POLICY-REF element

A policy reference file may refer to multiple P3P policies, specifying information about each. The POLICY-REF element describes attributes of a single P3P policy. Elements within the POLICY-REF element give the location of the policy and specify the areas of URI-space (and cookies) that each policy covers.

2.3.2.5 The INCLUDE and EXCLUDE elements

Each INCLUDE or EXCLUDE element specifies one local URI or set of local URIs. A set of URIs is specified if the wildcard character '*' is used in the URI-pattern. These elements are used to specify the portion of the Web site that is covered by the policy referenced by the enclosing POLICY-REF element.

When INCLUDE (and optionally, EXCLUDE) elements are present in a POLICY-REF element, it means that the policy specified in the about attribute of the POLICY-REF element applies to all the URIs at the requested host corresponding to the local-URI(s) matched by any of the INCLUDEs, but not matched by an EXCLUDE element.

A policy referenced in a policy reference file can be applied only to URIs on the DNS (Domain Name System) host that references it. Thus, for example, a policy reference file at the well-known location of host www.example.com can apply policies only to resources on www.example.com. However, if foo.example.com includes a P3P HTTP header in its responses that references a policy reference file on bar.example.com, that policy reference file would be applied to resources on foo.example.com (not bar.example.com or www.example.com). The same policy reference file might be referenced in P3P HTTP headers sent by multiple hosts, in which case it may be applied to each host that references it. The INCLUDE and EXCLUDE elements MUST specify URI patterns relative to the root of the DNS host to which they are applied. This requirement does NOT apply to the location of the P3P policy file (the about attribute on the POLICY-REF element).

If a METHOD element (section 2.3.2.8) specifies one or more methods for an enclosing policy reference, it follows that all methods not mentioned are consequently not covered by this policy. In the case that this is the only policy reference for a given URI prefix, user agents MUST assume that NO policy is in effect for all methods NOT mentioned in the policy reference file. It is legal but pointless to supply a METHOD element without any INCLUDE or COOKIE-INCLUDE elements.

It is legal, but pointless, to supply an EXCLUDE element without any INCLUDE elements; in that case, the EXCLUDE element MUST be ignored by user agents.

Note that the set of URIs specified with INCLUDE and EXCLUDE does not include cookies that might be set or replayed when requesting one of such URIs: in order to associate policies with cookies, the COOKIE-INCLUDE and COOKIE-EXCLUDE elements are needed.

2.3.2.6 The HINT element

Policy reference hints are a performance optimization that can be used under certain conditions. A site may declare a policy reference for itself using the well-known location, the P3P response header, or the HTML/XHTML link tag. It MAY further provide a hint to additional policy references, such as those declared by other sites.

For example, an HTML page might hint at policy references for its hyperlinks, embedded content, and action URIs. User agents MAY use the hint mechanism to discover policy reference files before requesting the affected URIs when the policy references are not available from the well-known location.

User agents which use hints to retrieve policies MUST NOT apply them to any site other than the one which contains the hinted policy reference file.

Any policy reference file MAY contain zero or more policy reference hints. Each hint is contained in a HINT element with two attributes, scope and path.

The scope attribute is used to specify a URI scheme and authority to which the hinted policy reference can be applied. If the authority component (cf. [URI]) is a server component (e.g., a hostname or IP address) the host part of the authority MAY begin with a wildcard, as defined in Section 2.3.2.1.2. The scope attribute MUST NOT contain a wildcard in any other position, MUST be encoded according to the conventions in Section 2.3.2.1.2, and MUST NOT contain a path, query or fragment URI component. Additionally, if the authority is a server, it SHOULD NOT contain a userinfo part.

The path attribute is used to locate the policy reference file on the hinted site. It is a relative URI whose base is the URI scheme and authority matched in the scope attribute. The path attribute MUST NOT be an absolute URI, so that the policy reference file is always retrieved from the same site that it is applied to.

2.3.2.7 The COOKIE-INCLUDE and COOKIE-EXCLUDE elements

The COOKIE-INCLUDE and COOKIE-EXCLUDE elements are used to associate policies to cookies (cf. [COOKIES] and [STATE]).

A cookie policy MUST cover any data (within the scope of P3P) that is stored in that cookie or linked via that cookie. It MUST also reference all purposes associated with data stored in that cookie or enabled by that cookie. In addition, any data/purpose stored or linked via a cookie MUST also be put in the cookie policy. In addition, if that linked data is collected by HTTP, then the policy that covers that GET/POST/whatever request must cover that data collection. For example, when CatalogExample asks customers to fill out a form with their name, billing, and shipping information, the P3P policy that covers the form submittal will disclose that CatalogExample collects this data and explain how it is used. If CatalogExample sets a cookie so that it can recognize its customers and observe their behavior on its Web site, it would have a separate policy for this cookie. However, if this cookie is also linked to the user's name, billing, and shipping information -- perhaps so CatalogExample can generate custom catalog pages based on where the customer lives -- then that data must also be disclosed in the cookie policy.

For the purpose of this specification, state management mechanisms use either SET-COOKIE or SET-COOKIE2 headers, and cookie-namespace is defined as the value of the NAME, VALUE, Domain and Path attributes, specified in [COOKIES] and [STATE].

Each COOKIE-INCLUDE or COOKIE-EXCLUDE element can be used to match (similarly to INCLUDE and EXCLUDE) the NAME, VALUE, Domain and Path components of a cookie, expressing the cookies which are covered by the policy specified by the about attribute when the cookies are set from the resources on the Web site where the policy reference file resides:

If the value of the domain attribute is set to the dot character ("."), the domain will match only cookies that omit the domain attribute (and thus have domain equivalent to the request host as per RFC 2965 ([STATE]).

Cookies that omit the path attribute have the default path of the request URI that generated the set-cookie response as per RFC 2965 [STATE]. The path attribute of a COOKIE-INCLUDE should be matched against this default value if a cookie omits the path attribute.

All four attributes are optional. If an attribute is absent, the COOKIE-INCLUDE (resp. COOKIE-EXCLUDE) will match cookies that have that attribute set to any value.

When COOKIE-INCLUDE (and optionally, COOKIE-EXCLUDE) elements are present in a POLICY-REF element, the policy specified in the about attribute of the POLICY-REF element applies to every cookie that is matched by any COOKIE-INCLUDE's, and not matched by a COOKIE-EXCLUDE element.

User agents MUST interpret COOKIE-INCLUDE and COOKIE-EXCLUDE elements in a policy reference file to determine the policy that applies to cookies set by or replayed to the host to which the policy reference file applies. While the domain attribute of a COOKIE-INCLUDE may match more broadly (for example, if the domain attribute is omitted it defaults to matching any domain value), user agents MUST limit their application of the policy to domains that could be legally used in a cookie set by the host to which the policy reference file applies. For example, if abc.xyz.example.com declares a policyref with <COOKIE-INCLUDE domain="*.xyz.*ple.com"/>, this would be matched to cookies with domains such as .abc.xyz.example.com and .xyz.example.com, but not .example.com or .xyz.sample.com.

A P3P policy can be associated with a cookie by the host that set that cookie as well as by any or all of the hosts to which it might be replayed. A user agent MAY fetch a cookie policy at the time a cookie is set and apply it later when the cookie is replayed, perhaps to other hosts in the domain. A user agent MAY request a policy reference file from a host before replaying a cookie to that host, and if the policy reference file contains an appropriate COOKIE-INCLUDE, a policy will be applied to that cookie even if the cookie was not set by that host. Any host to which the cookie may be replayed MUST be able to honor all the policies associated with the cookie, regardless of whether that host declares a policy for that cookie. Thus sites that set cookies that may be replayed to multiple hosts within a domain need to coordinate to make sure all the hosts can follow the declared policy. In addition, sites should be cautious with their use of wildcards to make sure that they do not inadvertently apply a policy to cookies to which it should not be applied (including previously set cookies that are still in use and cookies set by other hosts in the domain).

The policy that applies to a cookie applies until the policy expires, even if the associated policy reference file expires prior to policy expiry (but after the cookie was set). If the policy associated with a cookie has expired, then the user agent SHOULD reevaluate the cookie policy before sending the cookie. In addition, user agents MUST use only non-expired policies and policy reference files when evaluating new set-cookie events.

User agents that evaluate cookie policies SHOULD perform this evaluation *and its resultant behavior* before setting a cookie so that the cookie can be discarded without being set if that is what is dictated by the user's preferences.

Example 2.5 states that /P3P/Policies.xml#first applies to all cookies, except cookies with the cookie name value of "obnoxious-cookie", a domain value of ".example.com", and a path value of "/", and that /P3P/Policies.xml#second applies to all cookies with the cookie name of "obnoxious-cookie", a domain value of ".example.com", and a path value of "/".

Note that [STATE] states default values for the domain and path attributes of cookies: these should be used in the comparison if those attributes are not found in a specific cookie. Also, conforming to [STATE], if an explicitly specified Domain value does not start with a full stop ("."), the user agent MUST prepend a full stop for it; and, note that every Path begins with the "/" character.

2.3.2.8 The METHOD element

By default, a policy reference applies to the stated URIs regardless of the method used to access the resource. However, a Web site may wish to define different P3P policies depending on the method to be applied to a resource. For example, a site may wish to collect more data from users when they are performing PUT or DELETE methods than when performing GET methods.

The METHOD element in a policy reference file is used to state that the enclosing policy reference only applies when the specified methods are used to access the referenced resources. The METHOD element may be repeated to indicate multiple applicable methods. If the METHOD element is not present in a POLICY-REF element, then that POLICY-REF element covers the resources indicated regardless of the method used to access them.

So, to state that /P3P/Policies.xml#first applies to all resources whose paths begin with /docs/ for GET and HEAD methods, while /P3P/Policies.xml#second applies for PUT and DELETE methods, the following policy reference would be written:

Note that HTTP requires the same behavior for GET and HEAD requests, thus it is inappropriate to specify different P3P policies for these methods. The syntax for the METHOD element is:

Finally, note that the METHOD element is designed to be used in conjunction with INCLUDE or COOKIE-INCLUDE elements. A METHOD element by itself will never apply a POLICY-REF to a URI.

2.3.2.9 Domain Relationships

This section describes a method to allow user agents to recognize when hosts in different domains are owned by the same entity or entities acting as agents for one another. User agents may use this information when applying privacy preferences, particularly to avoid implementation issues encountered when more stringent privacy preferences are applied to domains that are deemed to be owned by third-parties. See [Coremetrics]

2.3.2.9.1 OUR-HOST Extension

The OUR-HOST element allows sites to declare hosts that are owned by the entity in the associated policy or that are acting as agents of that entity. User agents may use this extension to distinguish between such a host and actual third-party hosts.

The attribute name is a host name qualifier that can be a full individual host/domain name (e.g. www.example.com) or a wildcard qualifier describing a set of hosts/domains.

Here, authorityis defined as per RFC 2396 [URI], with the addition that the '*' character is to be treated as a wildcard, as defined in section 2.3.2.1.2.

The OUR-HOSTelement is declared in the POLICY-REF element. For URIs covered by the associated policy, the user agent can encounter other hosts in different domains serving embedded content, link, or action requests. The user agent may consider such a host to be owned by the same entity or one of its agents if its URI matches an associated OUR-HOST entry. Any number of OUR-HOSTelements can be declared inside a POLICY-REFelement.

Embedded content is considered to be any content that is retrieved during the processing of the current document, such as images, documents in frames, script files, etc. Content embedded more than 1 level deep (e.g. an image inside a frame) is still considered embedded content and the OUR-HOST declarations at the top-level may still apply.

Any relationships inferred by this mechanism are valid only in the context for which they were discovered -- this is not a mechanism for declaring globally that two hosts have a relationship in all contexts. By extension, the relationships are not transitive. Suppose two distinct hosts A and C are matched by OUR-HOST entries in a policy reference file for host B. Even if the same policy applies to both, nothing may be inferred about the relationship between A and C for use in other contexts. The relationships are not transitive even in the case of multi-level embedded content -- the top-level host must declare OUR-HOST relationships for all levels of embedded content.

In this example, example.com and example.net are owned by the same company. The example.net file has an OUR-HOST declaration for hosts in the example.com domain.

The following example.com policy reference file shows two policies and two OUR-HOSTdeclarations. The first declaration is for hosts in the example.net domain and applies to all URIs except for ones that begin with "/surveys/". The second OUR-HOST declaration is for hosts in the example.org domain and applies to all URIs that begin with "/surveys/". Since the example.net domain is not declared with this policy reference, user agents can not verify a relationship between example.com and example.net hosts for the survey URIs.

Browsers may cache the policy reference file based on its EXPIRY element. The expiration information associated with that element should also be considered to apply to the OUR-HOST declarations; i.e. that information may be cached along with the policy reference information.

The use of the OUR-HOST extension is optional. This extension provides more information that user agents may use in applying users' privacy preferences.

2.3.2.9.2 Cookie Playback

If a user agent allows a cookie to be set based on a relationship established by OUR-HOST declarations, it should verify that such a relationship exists at cookie playback time, and not send the cookie if not. When not using compact policies, such verification implies re-fetching an expired policy reference file and evaluating its OUR-HOST declarations.

2.3.2.9.3 Extension to P3P Compact Policy Header

Hosts may return an special token ("OHO:") in the P3P compact policy header to indicate OUR-HOST relationships. This token is followed by a comma-delimited list of hostname qualifiers that describe hosts that are owned by the same entity as the current host or that are acting as agents of the current host. This list is equivalent to the OUR-HOST declarations in the policy reference file, but it may be applied when using compact policies. In the example above, example.com could return the header:

Hosts returning embedded content are not required to declare a corresponding OHO token in their compact policies.

This token is optional and may be ignored by user agents. The syntax for the token is as follows:

Here, authorityis defined as per RFC 2396 [URI], with the addition that the '*' character is to be treated as a wildcard, as defined in section 2.3.2.1.2.

2.3.3 Applying a Policy to a URI

A policy reference file specifies the policy which applies to a given URI. In other words, the indicated policy describes all effects of dereferencing the given URI (in some cases, with the appropriately specified METHOD).

There is a general rule which describes what it means for a P3P policy to cover a URI: the referenced policy MUST cover actions that the user's client software is expected to perform as a result of requesting that URI. Obviously, the policy must describe all data collection performed by site as a result of processing the request for the URI. Thus, if a given URI is covered for terms of GET requests, then the policy given by the policy reference file MUST describe all data collection performed by the site when that URI is dereferenced. Likewise, if a URI is covered for POST requests, then any data collection that occurs as a result of POSTing a form or other content to that URI MUST be described by the policy.

The concept of "actions that the client software is expected to perform" includes the setting of client-side cookies or other state-management mechanisms invoked by the response. If executable code is returned when a URI is requested, then the P3P policy covering that URI MUST cover certain actions which will occur when that code is executed. The covered actions are any actions which could take place without the user explicitly invoking them. If explicit user action causes data to be collected, then the P3P policy covering the URI for that action would disclose that data collection.

2.3.4 Forms and Related Mechanisms

Forms deserve special consideration, as they often link to CGI scripts or other server-side applications in their action URIs (the action URI is the URI given in the action attribute of the HTML <FORM> element, as defined in section 17.3 of [HTML]). It is often the case that those action URIs are covered by a different policy than the form itself.

If a user agent is unable to find a matching include-rule for a given action URI in the policy reference file that was referenced from the page, it SHOULD assume that no policy is in effect. Under these circumstances, user agents SHOULD check the well-known location on the host of the action URI to attempt to find a policy reference file that covers the action URI. If this does not provide a P3P policy to cover the action URI, then a user agent MAY try to retrieve the policy reference file by using the HINT mechanism on the action URI, and/or by issuing a HEAD request to the action URI before actually submitting any data in order to find the policy in effect. Services SHOULD ensure that server-side applications can properly respond to such HEAD requests and return the corresponding policy reference link in the headers. In case the underlying application does not understand the HEAD request and no policy has been predeclared for the action URI in question, user agents MUST assume that no policy is in effect and SHOULD inform the user about this or take the corresponding actions according to the user's preferences.

Note that services might want to make use of the <METHOD> element in order to declare policies for server-side applications that only cover a subset of supported methods, e.g., POST or GET. Under such circumstances, it is acceptable that the application in question only supports the methods given in the policy reference file (e.g., PUT requests need not be supported). User agents SHOULD NOT attempt to issue a HEAD request to an action URI if the relevant methods specified in the form's method attribute have been properly predeclared in the page's policy reference file.

In some cases, different data is collected at the same action URI depending on some selection in the form. For example, a search service might offer to both search for people (by name and/or email) and (arbitrary) images. Using a set of radio buttons on the form, a single server-side application located at one and the same action URI handles both cases and collects the required information necessary for the search. If a service wants to predeclare the data collection practices of the server-side application it MAY declare all of the data collection practices in a single policy file (using a <INCLUDE> declaration matching the action URI). In this case, user agents MUST assume that all data elements are collected under every circumstance. This solution offers the convenience of a single policy but might not properly reflect the fact that only parts of the listed data elements are collected at a time. Services SHOULD make sure that a simple HEAD request to the action URI (i.e., without any arguments, especially without the value of the selected radio button) will return a policy that covers all cases.

Note that if a form is handled through use of the GET method, then the action URI reflects the choice of form elements selected by the user. In some cases, it will be possible to make use of the wildcard syntax allowed in policy reference files to specify different policies for different uses of the same form action-handler URI. Therefore, user agents MUST include the query-string portion of URIs when making comparisons with INCLUDE and EXCLUDE elements in policy reference files.

2.4 Additional Requirements

2.4.1 Non-ambiguity

User agents need to be able to determine unambiguously what policy applies to a given URI. Therefore, sites SHOULD avoid declaring more than one non-expired policy for a given URI. In some rare case sites MAY declare more than one non-expired policy for a given URI, for example, during a transition period when the site is changing its policy. In those cases, the site will probably not be able to determine reliably which policy any given user has seen, and thus it MUST honor all policies (this is also the case for compact policies, cf. Section 4.1 . Sites MUST be cautious in their practices when they declare multiple policies for a given URI, and ensure that they can actually honor all policies simultaneously.

If a policy reference file at the well-known location declares a non-expired policy for a given URI, this policy applies, regardless of any conflicting policy reference files referenced through HTTP headers or HTML/XHTML link tags.

If an HTTP response header includes references to more than one policy reference file, P3P user agents MUST ignore all references after the first one.

If an HTML (resp. XHTML) file includes HTML (resp. XHTML) link tag references to more than one policy reference file, P3P user agents MUST ignore all references after the first one.

If a user agent discovers more than one non-expired P3P policy for a given URI (for example because a page has both a P3P header and a link tag that reference different policy reference files, or because P3P headers for two pages on the site reference different policy reference files that declare different policies for the same URI), the user agent MAY assume any (or all) of these policies apply as the site MUST honor all of them.

2.4.2 Multiple Languages

Multiple language versions (translations) of the same policy can be offered by the server using the HTTP "Content-Language" header to properly indicate that a particular language has been used for the policy. This is useful so that human-readable fields such as entity and consequence can be presented in multiple languages. The same mechanism can also be used to offer multiple language versions for data schemas. Servers SHOULD return a localized policy in response to an HTTP request with an HTTP "Accept-Language" header when a policy matching the given language preferences is available.

Whenever Content-Language is used to distinguish policies at the same URI that are offered in multiple languages, the policies MUST have the same meaning in each language. Two policies (or two data schemas) are taken to be identical if

Due to the use of the Accept-Language mechanism, implementers should take note that user agents may see different language versions of a policy or policy reference file despite sending the same Accept-Language request header if a new language version of a policy or data schema has been added.

Finally, language declarations can be also included directly within P3P XML files: the POLICY, POLICIES, META, and DATASCHEMA elements MAY take an xml:lang attribute to indicate the language of any human-readable fields they contain (xml:lang is normatively defined in section 2.12 of [XML]).

2.4.3 The Safe Zone

P3P defines a special set of "safe zone" practices, which SHOULD be used by all P3P-enabled user agents and services for the communications which take place as part of fetching a P3P policy or policy reference file. In particular, requests to the well-known location for policy reference files SHOULD be covered by these "safe zone" practices. Communications covered by the safe zone practices SHOULD have only minimal data collection, and any data that is collected is used only in non-identifiable ways.

To support this safe zone, P3P user agents SHOULD suppress the transmission of data unnecessary for the purpose of finding a site's policy until the policy has been fetched. Therefore safe-zone practices for user agents include the following requirements:

Note that the safe zone requirements do not say that sites cannot keep identifiable information -- only that they SHOULD NOT use in an identifiable way any information collected while serving a policy file or policy reference file. Tracking down the source of a denial of service attack, for example, would be a legitimate reason to use this information.

2.4.4 Policy and Policy Reference File Processing by User Agents

P3P user agents MUST only render or act upon P3P policies and policy reference files that are well-formed XML.

P3P user agents SHOULD only render or act upon P3P policies and policy reference files that conform to the XML schema given in Appendix 4, and user agents SHOULD NOT rely upon any part of a policy or policy reference file that does not conform to this XML schema.

User agents MUST NOT locally modify a P3P policy or policy reference file in order to make it conform to the XML schema.

2.4.5 Security of Policy Transport

P3P policies and references to P3P policies SHOULD NOT contain any sensitive information. This means that there are no additional security requirements for transporting a reference to a P3P policy beyond the requirements of the document it is associated with; so, if an HTML document would normally be served over a non-encrypted session, then P3P does not require nor recommend that the document be served over an encrypted session when a reference to a P3P policy is included with that document.

2.4.6 Policy Updates

Note that when a Web site changes its P3P policy, the old policy applies to data collected when it was in effect. It is the responsibility of the site to keep records of past P3P policies and policy reference files along with the dates when they were in effect, and to apply these policies appropriately.

If a site wishes to apply a new P3P policy to previously collected data, it MUST provide appropriate notice and opportunities for users to accept the new policy that are consistent with applicable laws, industry guidelines, or other privacy-related agreements the site has made.

2.4.7 Absence of Policy Reference File

If no policy reference file is available for a given site, user agents MUST assume (an empty) policy reference file exists at the well-known location with a 24 hour expiry, and therefore if the user returns to the site after 24 hours, the user agent MUST attempt to fetch a policy reference file from the well-known location again. User agents MAY check the well-known location more frequently, or upon a certain event such as the user clicking a browser refresh button. Sites MAY place a policy reference file at the well-known location that indicates that no policy is available, but set the expiry such that user agents know they need not check every 24 hours.

2.4.8 Asynchronous Evaluation

User agents MAY asynchronously fetch and evaluate P3P policies. That is, P3P policies need not necessarily be fetched and evaluated prior to other HTTP transactions.This behavior may be dependent on the the user's preferences and the type of request being made. Until a policy is evaluated, the user agent SHOULD treat the site as if it has no privacy policy. Once the policy has been evaluated, the user agent SHOULD apply the user's preferences. To promote deterministic behavior, the user agent SHOULD defer application of a policy until a consistent point in time. For example, a Web browser might apply a user's preferences just after the user agent completes a navigation, or when confirming a form submission.

2.5. The P3P Generic Attribute for XML Applications

P3P 1.0 was designed to associate XML-encoded privacy policies with URIs, sets of URIs, or cookies. P3P 1.0 is well suited for use with HTML and XHTML pages transmitted over [HTTP1.1] or [HTTP1.0]. However, P3P 1.0 cannot be used in situations where a request is not directed to a URI, for example, some applications of Web Services and SOAP. In addition, P3P 1.0 cannot be used in situations where policies apply to only a subset of the content associated with a given URI. For example, while P3P 1.0 can be used to apply a P3P policy to an entire form specified by XForms, it cannot be used to apply the policy to only a single form field.

The P3P 1.1 Specification provides a new binding mechanism to allow for increased granularity beyond the URI level and to allow policies to apply to content not associated with a URI. The new mechanism takes the form of a generic attribute (similar to xml:lang) that binds a P3P policy to an XML element.

A P3P policy referenced by the P3P generic attribute MUST apply to all data collection performed as a result of processing the elementcarrying the P3P Generic Attribute. The policy also MUST describe all data collection performed as a result of the processing of all subelements.

For all XML applications in which the P3P Generic Attribute is to be used, the attribute MUST be imported into the relevant XML schema.

If the element is re-used by mechanisms such as XInclude or the SVG <use> Element, the Policy applies also in the new context where the element is re-used. The policy is sticky to the element from which it is referenced.

The P3P Generic Attribute is designed for use in XML elements that describe interfaces, not XML elements that encode user data. Thus, it is meaningful to use the P3P Generic Attribute to associate a P3P policy with a blank form or form field. The semantics of such an association are that any data entered into the form will be processed in a manner consistent with the P3P policy. It is not meaningful to use the P3P Generic Attribute to associate a P3P policy with data a user has entered into a form.

The P3P Generic Attribute MUST NOT be used in applications, such as RDF, that do not have a tree structure because its semantics relies on the concept of subelements. In the case of RDF, one of the other three binding mechanisms described in 2. Referencing Policies may be used, as RDF makes use of URIs.

The P3P generic attribute takes a URI of a valid P3P 1.1 policy as its value. The P3P generic attribute MUST NOT reference a P3P

Policy
Reference File

2.6 Example Scenarios

As an aid to sites deploying P3P, several example scenarios are presented, along with descriptions of how P3P is used on those sites.

Scenario 1: Web site basic.example.com uses a variety of images, all of which it hosts. It also includes some forms, which are all submitted directly to the site. This site can declare a single P3P policy for the entire site (or if different privacy policies apply to different parts of the site, it can declare multiple P3P policies). As long as all of the images and form action URIs are in directories covered by the site's P3P policy, user agents will automatically recognize the images and forms as covered by the site's policy.

Scenario 2: Web site busy.example.com uses a content distribution network called cdn.example.com to host its images so as to reduce the load on its servers. Thus, all of the images on the site have URIs at cdn.example.com. CDN acts as an agent to Busy in this situation, and collects no data other than log data. This log data is used only for Web site and system administration in support of providing the services that Busy contracted for. Busy's privacy policy applies to the images hosted by CDN, so Busy uses the HINT element in its policy reference file to point to a suitable policy reference file at CDN, indicating that such images are covered by example.com P3P policy.

Scenario 3: Web site busy.example.com also has a contract with an advertising company called clickads.example.com to provide banner ads on its site. The contract allows Clickads to set cookies so as to make sure each user does not see a given ad more than three times. Clickads collects statistics on how many users view each ad and reports them to the companies whose products are being advertised. But these reports do not reveal information about any individual users. As was the case in Scenario 2, Busy's privacy policies applies to these ads hosted by Clickads, so Busy uses the HINT element in its policy reference file to point to a suitable policy reference file at Clickads, indicating that Busy P3P policy applies to such embedded content served by clickads.example.com. The companies whose products are being advertised need not be mentioned in the Busy privacy policy because the only data they are receiving is aggregate data.

Scenario 4: Web site busy.example.com also has a contract with funchat.example.com to host a chat room for its users. When users enter the chat room they are actually leaving the Busy site. However, the chat room has the Busy logo and is actually covered by the Busy privacy policy. In this instance Funchat is acting as an agent for Busy, but -- unlike the previous examples -- their content is not embedded in the Busy site. Busy can use the HINT element in its policy reference file to point to a suitable Funchat policy reference file, that indicates that Funchat chat room is covered by Busy privacy policy, therefore facilitating a smoother transition to the chat room.

Scenario 5: Web site bigsearch.example.com has a form that allows users to type in a search query and have it performed on their choice of search engines located on other sites. When a user clicks the "submit" button, the search query is actually submitted directly to these search engines -- the action URI is not on bigsearch.example.com but rather on the search engine selected by the user. Bigsearch can declare the privacy policies for these search engines by using the HINT element to point to their corresponding policy reference files. So when a user clicks the "submit" button, their user agent can check its privacy policy before posting any data. In order to make this search choice mechanism work, Bigsearch might actually have a form with an action URI on its own site, which redirects to the appropriate search engine. In this case, the user agent should check the search engine privacy policy upon receiving the redirect response.

Scenario 6: Web site bigsearch.example.com also has a form that allows users to type in a search query and have it simultaneously performed on ten different search engines. Bigsearch submits the queries, gets back the results from each search engine, removes the duplicates, and presents the results to the user. In this case, the user interacts only with Bigsearch. Thus, the only P3P policy involved is the one that covers the Bigsearch Web site. However, Bigsearch must disclose that it shares the users' search queries with third parties (the search Web sites), unless Bigsearch has a contract with these search engines and they act as agents to Bigsearch.

Scenario 7: Web site bigsearch.example.com also has banner advertisements provided by a company called adnetwork.example.com. Adnetwork uses cookies to develop profiles of users across many different Web sites so that it can provide them with ads better suited to their interests. Because the data about the sites that users are visiting is being used for purposes other than just serving ads on the Bigsearch Web site, Adnetwork cannot be considered an agent in this context. Adnetwork must create its own P3P policy and use its own policy reference file to indicate what content it applies to. In addition, Bigsearch may optionally use the HINT element in its policy reference file to indicate that the Adnetwork P3P policy reference file applies to these advertisements. Bigsearch should only do this if Adnetwork has told it what P3P policy applies to these advertisements and has agreed to notify Bigsearch if the policy reference needs to be changed.

Scenario 8: Web site busy.example.com uses cookies throughout its Web site. It discloses a cookie policy, separate from its regular P3P policy to cover these cookies. It uses the COOKIE-INCLUDE element in its policy reference file to declare the appropriate policy for these cookies. As a performance optimization, it also makes available a compact policy by sending a P3P header that includes this compact policy whenever it sets a cookie.

Scenario 9: Web site config.example.com provides a service in which they optimize various kinds of Web content based on each user's computer and Internet configuration. Users go to the Config Web site and answer questions about their computer, monitor, and Internet connection. Config encodes the responses and stores them in a cookie. Later, when the user is visiting Busy -- a Web site that has contracted with Config -- whenever the browser requests content that can be optimized (certain images, audio files, etc.), Busy will redirect the user to Config, which will read the user's cookie, and deliver the appropriate content. In this case, Config should declare a privacy policy that describes the kinds of data collected and stored in its cookies, and how that data is used. It should use a COOKIE-INCLUDE element in its policy reference file to declare the policy for the cookies. It will probably reference Busy's P3P policy for the actual images or audio files delivered, as it is acting much like CDN acts in scenario 2. Busy will probably also use HINT elements in its policy reference file to reference the policy for the Config-delivered content.

3. Policy Syntax and Semantics

P3P policies are encoded in XML with namespaces (see [XML] and [XML-Name]). A possible encoding using the RDF data model ([RDF]) is provided in [P3P-RDF].

Section 3.1 begins with an example of an English language privacy policy and a corresponding P3P policy. P3P policies include general assertions that apply to the entire policy as well as specific assertions -- called statements -- that apply only to the handling of particular types of data referred to by data references. Section 3.2 describes the POLICY element and policy-level assertions. Section 3.3 describes statements and data references.

3.1 Example policies

3.1.1 English language policies

The following are two examples of English-language privacy policy to be encoded as a P3P policy. Both policies are for one example company, CatalogExample, which has different policies for those browsing their site and those actually purchasing products. Example 3.1. is provided in both English and as a more formal description using P3P element and attribute names.

Here is Example 3.1 in a more formal description, using the P3P element and attribute names [with the section of the spec that was used cited in brackets for easy reference]:

3.1.2 XML encoding of policies

The following pieces of [XML] capture the information as expressed in the above two examples. P3P policies are statements that are properly expressed as well-formed XML. The policy syntax will be explained in more detail in the sections that follow.

3.2 Policies

This section defines the syntax and semantics of P3P policies. All policies MUST be encoded using [UTF-8].

In cases where the P3P vocabulary is not precise enough to describe a Web site's practices, sites should use the vocabulary terms that most closely match their practices and provide further explanation in the CONSEQUENCE field and/or their human-readable policy. However, policies MUST NOT make false or misleading statements.

3.2.1 The POLICIES element

The POLICIES element gathers one or more P3P policies together in a single file. This is provided as a performance optimization: many policies can be collected with a single request, improving network traffic and caching.

A POLICIES element is the root element of policy files. Further, the POLICIES element can be put within the policy reference file, inside the META element:: in this case, user agents need only fetch a single file, containing both the policy reference file and the policies.

The POLICIES element can optionally contain an xml:lang attribute (see section 2.4.2), an EXPIRY element, indicating the expiration of the included policies, and an embedded data schema using the DATASCHEMA element (see Section 5).

Since policies are included in a POLICIES element, each MUST have a name attribute which is unique in the file. This allows policy references (in POLICY-REF elements) to link to that policy.

The file in http://www.example.com/Shop/policies.xml could have the following content:

The files in http://www.example.com/Shop/CDs/* could then be associated to the second policy ("policy2") using the following policy reference file in http://www.example.com/w3c/p3p.xml :

3.2.2 The POLICY element

The POLICY element contains a complete P3P policy. Each P3P policy MUST contain exactly one POLICY element. The policy element MUST contain an ENTITY element that identifies the legal entity making the representation of the privacy practices contained in the policy. In addition, the policy element MUST contain an ACCESS element and one or more STATEMENT elements.It SHOULD contain a DISPUTES-GROUP element. It may contain a P3P data schema and one or more extensions.

3.2.3 STATEMENT-GROUP-DEF element (EXTENSION)

The STATEMENT-GROUP-DEF extension is used to define an identifier and optionally properties that can be applied to a group of STATEMENT elements using the STATEMENT-GROUP extension. P3P user agents that understand these two extensions MAY take this information into account when displaying P3P policy information for users. For example, statements that belong to the same group might be displayed together under a single heading.

(Note that the optional attribute does not need to be explicitly included because its default value is yes.)

Because P3P 1.0 user agents are unaware of this extension (and thus will ignore it), all statements that belong to statement groups that have consent attributes with values of opt-in, opt-out, MUST use the corresponding required attribute on all PURPOSE and RECIPIENTS elements. If consent="always" the required attribute MUST be omitted as its default value is always. Any user agent that relies on this extension MUST check to make sure this requirement has been followed. If a user agent finds an inconsistency between a consent attribute and a required attribute it MUST either ignore the extension altogether or treat the statement group as if its consent value was mixed.

Note that the purpose current and the recipient ours do not take a required attribute and thus cannot be used in statement groups with consent values other than required or mixed.

Statement groups are intended primarily as hints to user agents on how to display P3P policy information to users. As currently specified, they are not intended for use in automated decision-making. For example, user agents cannot make judgments automatically about which statement groups apply to the activities of their users.

3.2.4 The TEST element

The TEST element is used for testing purposes: the presence of TEST in a policy indicates that the policy is just an example, and as such, it MUST be ignored, and not be considered as a valid P3P policy.

3.2.5 The ENTITY element

The ENTITY element gives a precise description of the legal entity making the representation of the privacy practices.

The ENTITY element contains a description of the legal entity consisting of DATA elements referencing (all or some of) the fields of the business dataset: it MUST contain both the legal entity's name and one or more contact information fields among postal address, telephone number, email address, URI. Note that some laws and codes of conduct require entities to include a postal address or other specific information in their contact information.

Although it is permissable for a particular DATA element to appear more than once within a single ENTITY element, this is not recommended as user agents may not display multiple instances of a DATA element correctly. Policy writers who wish to indicate multiple points of contact for customer service at a web site should use the DISPUTES element, which is designed to have multiple instances.

3.2.6 The ACCESS element

The ACCESS element indicates whether the site provides access to various kinds of information.

3.2.7 The DISPUTES element

A policy SHOULD contain a DISPUTES-GROUP element, which contains one or more DISPUTES elements. These elements describe dispute resolution procedures that may be followed for disputes about an entity's privacy practices. Each DISPUTES element can optionally contain a LONG-DESCRIPTION element, an IMG element, and a REMEDIES element. Entities with multiple dispute resolution procedures should use a separate DISPUTES element for each. Since different dispute procedures have separate remedy processes, each DISPUTES element would need a separate LONG-DESCRIPTION, IMG tag and REMEDIES element, if they are being used.

The DISPUTES element can contain a LONG-DESCRIPTION element, where a human readable description is present: this should contain the name of the appropriate legal forum, applicable law, or third party organization; or contact information for customer service if not already provided at the service URI.

Note that there can be multiple assurance services, specified via multiple occurrences of DISPUTES within the DISPUTES-GROUP element. These fields are expected to be used in a number of ways, including representing that one's privacy practices are self assured, audited by a third party, or under the jurisdiction of a regulatory authority.

3.2.8 The REMEDIES element

Each DISPUTES element SHOULD contain a REMEDIES element that specifies the possible remedies in case a policy breach occurs.

3.3 Statements

Statements describe data practices that are applied to particular types of data.

3.3.1 The STATEMENT element

The STATEMENT element is a container that groups together a PURPOSE element, a RECIPIENT element, a RETENTION element, a DATA-GROUP element, and optionally a CONSEQUENCE element and one or more extensions. All of the data referenced by the DATA-GROUP is handled according to the disclosures made in the other elements contained by the statement. Thus, sites may group elements that are handled the same way and create a statement for each group. Sites that would prefer to disclose separate purposes and other information for each kind of data they collect can do so by creating a separate statement for each data element.

To simplify practice declaration, service providers may aggregate any of the disclosures (purposes, recipients, and retention) within a statement over data elements. Service providers MUST make such aggregations as an additive operation. For instance, a site that distributes your age to ours (ourselves and our agents), but distributes your postal code to unrelated (unrelated third parties), MAY say they distribute your name and postal code to ours and unrelated. Such a statement appears to distribute more data than actually happens. It is up to the service provider to determine if their disclosure deserves specificity or brevity. Note that when aggregating disclosures across statements that include the NON-IDENTIFIABLE element, this element may be included in the aggregated statement only if it would otherwise appear in every statement if the statements were written separately.

Also, one must always disclose all options that apply. Consider a site with the sole purpose of collecting information for the purposes of contact (Contacting Visitors for Marketing of Services or Products). Even though this is considered to be for the current (Completion and Support of Activity For Which Data Was Provided) purpose, the site must state both contact and current purposes. Consider a site which distributes information to ours in order to redistribute it to public: the site must state both ours and public recipients.

Service providers often aggregate data they collect. Sometimes this aggregate data may be used for different purposes than the original data, shared more widely than the original data, or retained longer than the original data. For example many sites publish or disclose to their advertisers statistics such as number of visitors to their Web site, percentage of visitors who fit into various demographic groups, etc. When aggregate statistics are used or shared such that it would not be possible to derive data for individual people or households based on these statistics, no disclosures about these statistics are necessary in a P3P policy. However, services MUST disclose the fact that the original data is collected and declare any use that is made of the data before it is aggregated.

3.3.2 The STATEMENT-GROUP element (EXTENSION)

A statement can be associated with a statement group. Each statement can have at most one <STATEMENT-GROUP> extension.

A STATEMENT-GROUP can carry at most two attributes: The id-attribute and the name-attribute:

The id-attribute associates a STATEMENT with a certain group of STATEMENTs to cluster them together to reflect a certain typical usage (see STATEMENT-GROUP-DEF for more information

The STATEMENT-GROUP is placed after the opening tag of the STATEMENT element.

The name-attribute associates a name to a certain statement. User agents may use this name to improve the display of the policy to the user in a human readable format. This extension was taken up from one implementer's authoring tool. Note that versions of this tool up through version 1.10 used an optional GROUP-INFO extension to name each statement. This extension provides the same function as the name attribute in the STATEMENT-GROUP extension. For backwards compatibility with existing P3P 1.0 policies, user agent implementers may wish to include support for this old extension. The old extension provided by the tool is placed after the opening tag of a STATEMENT element and takes the form

3.3.3 The CONSEQUENCE element

STATEMENT elements may optionally contain a CONSEQUENCE element that can be shown to a human user to provide further explanation about a site's practices.

The definition of CONSEQUENCE given here is somewhat different from the definition given in the P3P 1.0 specification, which stated that the element should be used for consequences that can be shown to a human user to explain why the suggested practice may be valuable in a particular instance even if the user would not normally allow the practice." The P3P 1.1 definition has been broadened to reflect how the CONSEQUENCEelement is being used by web sites in practice. As the P3P 1.1 definition subsumes the P3P 1.0 definition, it is not necessary for web sites that have developed their policies using the P3P 1.0 definition to change their policies unless they want to take advantage of the additional flexibility offered by the P3P 1.1 definition. See also Completeness of Human-Readable Translations .

3.3.4 The NON-IDENTIFIABLE element

A STATEMENT element may optionally contain the NON-IDENTIFIABLE element, signifying either that there is no data collected under this STATEMENT, or that all of the data referenced by that STATEMENT will be anonymized upon collection.

If the NON-IDENTIFIABLE element is present in any STATEMENT elements in a policy, then a human readable explanation of how the data is anonymized MUST be included or linked to at the discuri .

Also, if the NON-IDENTIFIABLE element is present in a STATEMENT then the other elements in that STATEMENT are optional.

3.3.5 The PURPOSE element

Each STATEMENT element that does not include a NON-IDENTIFIABLE element MUST contain a PURPOSE element that contains one or more purposes of data collection or uses of data. Sites MUST classify their data practices into one or more of the purposes specified below.

Each type of purpose (with the exception of current) can have the following optional attribute:

Service providers MUST use the above elements to explain the purpose of data collection. Service providers MUST disclose all that apply. If a service provider does not disclose that a data element will be used for a given purpose, that is a representation that data will not be used for that purpose. Service providers that disclose that they use data for "other" purposes MUST provide human readable explanations of those purposes.

3.3.5.1 The PPURPOSE element (EXTENSION)

The primary purpose extension element allows user agents to determine the primary reason why the data recipient is collecting data. Multiple primary purposes may be used.

The PPURPOSE is placed after the opening tag of the PURPOSE element. It is intended to expand upon the <current/> tag, providing a more detailed description of data usage.

In the following sample, information is primarily being provided to authenticate a user as well as provide web content.

3.3.6 The RECIPIENT element

Each STATEMENT element that does not include a NON-IDENTIFIABLE element MUST contain a RECIPIENT element that contains one or more recipients of the collected data. Sites MUST classify their recipients into one or more of the six recipients specified.

Service providers MUST disclose all the recipients that apply. P3P makes no distinctions about how that data is released to the recipient; it simply requires that if data is released, then that sharing must be disclosed in the P3P policy. Examples of disclosing data which MUST be covered by a P3P statement include:

Note that in some cases the above set of recipients may not completely describe all the recipients of data. For example, the issue of transaction facilitators, such as shipping or payment processors, who are necessary for the completion and support of the activity but may follow different practices was problematic. Currently, only delivery services can be explicitly represented in a policy. Other such transaction facilitators should be represented in whichever category most accurately reflects their practices with respect to the original service provider.

A special element for delivery services is included, but not one for payment processors (such as banks or credit card companies) for the following reasons: Financial institutions will typically have separate agreements with their customers regarding the use of their financial data, while delivery recipients typically do not have an opportunity to review a delivery service's privacy policy.

Note that the <delivery/> element SHOULD NOT be used for delivery services that agree to use data only on behalf of the service provider for completion of the delivery.

3.3.6.1 The JURISDICTION element (EXTENSION)

The jurisdiction extension element allows user agents to make judgments about the trustworthiness of a data recipient based on the regulatory environment they are placed in. Jurisdictions of recipients can be rendered machine readable by inserting a known URI into the service field (e.g. the URI of a body of legislation which applies). For example organizations within the European Union can be assumed to comply to European data protection law and could therefore insert the URI of the 95/46 directive as in the example above. Some jurisdictions prohibit transfer of data to certain other jurisdictions without the explicit consent of the data subject. It should be noted therefore declaring the data transfer activity of a recipient using the P3P jurisdiction extension is not sufficient to guarantee its legality.

3.3.7 The RETENTION element

Each STATEMENT element that does not include a NON-IDENTIFIABLE element MUST contain a RETENTION element that indicates the kind of retention policy that applies to the data referenced in that statement.

3.3.8 The DATA-GROUP and DATA elements

Each STATEMENT element that does not include a NON-IDENTIFIABLE element MUST contain at least one DATA-GROUP element that contains one or more DATA elements. DATA elements are used to describe the type of data that a site collects. A set of DATA Elements that every user-agent MUST be aware of is defined in Structure of Base Data Schema

Note that user agents should be cautious about using the optional attribute in automated decision-making. If the optional attribute is associated with a data element directly controlled by the user agent (such as the HTTP Referer header or cookies), the user agent should make sure that this data is not transmitted to Web sites at which a data element is optional if the site's policy would not match a user's preferences if the data element was required. Likewise, for data elements that users typically type into forms, user agents should alert users when a site's practices about optional data do not match their preferences.

DATA elements can contain the actual data (as already sen in the case of the ENTITY element), and can contain related category information.

For example, to reference the user's home address city, all the elements of the data set user.business-info and (optionally) all the elements of the data set user.home-info.telecom, the service would send the following references inside a P3P policy:

When the actual value of the data is known, it can be expressed inside the DATA element. For example, as seen in the example policies:

3.4 Categories and the CATEGORIES element

Categories are elements inside data elements that provide hints to users and user agents as to the intended uses of the data. Categories are vital to making P3P user agents easier to implement and use. Note that categories are not data elements: they just allow users to express more generalized preferences and rules over the exchange of their data. Categories SHOULD NOT be used within the DATA elements of an ENTITY element.

The Computer, Navigation, Interactive and Content categories can be distinguished as follows. The Computer category includes information about the user's computer including IP address and software configuration. Navigation data describes actual user behavior related to browsing. When an IP address is stored in a log file with information related to browsing activity, both the Computer category and the Navigation category should be used. Interactive Data is data actively solicited to provide some useful service at a site beyond browsing. Content is information exchanged on a site for the purposes of communication.

The Other category should be used only when data is requested that does not fit into any other category.

P3P uses categories to give users and user agents additional hints as to what type of information is requested from a service. While most data in the base data schema is in a known category (or a set of known categories), some data elements can be in a number of different categories, depending on the situation. The former are called fixed-category data elements (or "fixed data elements" for short), the latter variable-category data elements ("variable data elements"). Both types of elements are described in Section 5.2.2.

3.5 Extension Mechanism: the EXTENSION element

P3P provides a flexible and powerful mechanism to extend its syntax and semantics using one element: EXTENSION. This element is used to indicate portions of the policy/policy reference file/data schema which belong to an extension. The meaning of the data within the EXTENSION element is defined by the extension itself.

For example, if www.catalog.example.com would like to add to P3P a feature to indicate that a certain set of data elements were only to be collected from users living in the United States, Canada, or Mexico, it could add a mandatory extension like this:

On the other hand, if www.catalog.example.com would like to add an extension stating what country the server is in, an optional extension might be more appropriate, such as the following:

The xmlns attribute is significant since it specifies the namespace for interpreting the names of elements and attributes used in the extension. Note that, as specified in [XML-Name], the namespace URI is just intended to be a unique identifier for the XML entities used by the extension. Nevertheless, service providers MAY provide a page with a description of the extension at the corresponding URI.

The EXTENSION element can appear in various places within P3P syntax: such positions are normatively specified by the XML Schema present in Appendix 4 (and, informally specified by the ABNF syntax..

3.6 User Preferences

User agents MUST document a method by which preferences can be imported and processed, and SHOULD document a method by which preferences can be exported.

P3P user agents MUST act according to the preference settings selected by the user. This requires that they be able to process policy and policy reference files as appropriate to evaluate each policy with respect to a user's preferences or other criteria specified by the settings. Depending on these settings, this may require, for example, that the user agent verify that required parts of the P3P policy are present, or check that the syntax of the entire policy is valid.

4. Compact Policies

Compact policies are a performance optimization that is OPTIONAL for both user agents and servers. They represent only a summary of a site's full P3P policy for a cookie; the full P3P policy is the authoritative statement of policy. However, if a site makes compact policy statements, it MUST make these statements in good faith. User agents that are unable to obtain enough information from a compact policy to make a decision according to a user's preferences SHOULD fetch the full policy.

User agents that use compact policies as part of their decision making MUST include a mechanism that allows users to determine that a particular decision was made based on a compact policy and to view that compact policy. However, user agents that provide general information about a site's P3P policies to users MUST use the full P3P policy and MUST NOT use the compact policy for this purpose.

In P3P, compact policies contain policy information related to cookies (cf. [COOKIES] and [STATE]) only. The Web server is responsible for building a P3P compact policy to represent the cookies referenced in a full policy. The policy specified in a P3P compact policy applies to data stored within all cookies set in the same HTTP response as the compact policy, all cookies set by scripts associated with that HTTP response, and also to data linked to the cookies.

4.1 Referencing compact policies

Any HTTP resource MAY include a P3P compact policy through the P3P response header (cf. Section 2.2.2). If a site is using P3P headers, it SHOULD include this on responses for all appropriate request methods, including HEAD and OPTION requests.

The P3P compact policy header has a quoted string that may contain one or more delimited tokens (the "compact policy"). Tokens can appear in any order, and the space character (" ") is the only valid delimiter. The syntax for this header is as follows:

As for all HTTP headers, the name of the P3P header field is case-insensitive. The field-value (i.e., the content of the header) is instead case sensitive.

If an HTTP response includes more than one compact policy, P3P user agents MUST ignore all compact policies after the first one.

4.2 Compact Policy Vocabulary

P3P compact policies use tokens representing the following elements from the P3P vocabulary: ACCESS, CATEGORIES, DISPUTES, NON-INDENTIFIABLE, PURPOSE, RECIPIENT, REMEDIES, RETENTION, TEST.

If a token appears more than once in a single compact policy, the compact policy has the same semantics as if that token appeared only once. If an unrecognized token appears in a compact policy, the compact policy has the same semantics as if that token was not present.

The P3P compact policy vocabulary is expressed using a developer-readable language to reduce the number of bytes transferred over the wire within a HTTP response header. The syntax of the tokens follows:

4.2.1 Compact ACCESS

Information in the ACCESS element is represented in compact policies using tokens composed by a three letter code:

4.2.2 Compact DISPUTES

If a full P3P policy contains a DISPUTES-GROUP element that contains one or more DISPUTES elements, then the server should signal the user agent by providing a single "DSP" token in the P3P-compact policy field:

4.2.3 Compact REMEDIES

Information in the REMEDIES element is represented in compact policies as follows:

4.2.4 Compact NON-IDENTIFIABLE

The presence of the NON-IDENTIFIABLE element in every statement of the policy is signaled by the NID token (note that the NID token MUST NOT be used unless the NON-IDENTIFIABLE element is present in every statement within the policy):

4.2.5 Compact PURPOSE

Purposes are expressed in P3P compact policy format using tokens composed by a three letter code plus an optional one letter attribute. Such an optional attribute encodes the value of the "required" attribute in full P3P policies: its value can be "a", "i" and "o", which mean that the "required" attribute in the corresponding P3P policy must be set to "always", "opt-in" and "opt-out" respectively.

If a P3P compact policy needs to specify one or more other-purposes in its full P3P policy, a single OTP flag is used to signal the user agent that other-purposes exist in the full P3P policy.

The corresponding associations among P3P purposes and compact policy codes follow:

4.2.6 Compact RECIPIENT

Recipients are expressed in P3P compact policy format using a three letter code plus an optional one letter attribute. Such an optional attribute encodes the value of the "required" attribute in full P3P policies: its value can be "a", "i" and "o", which mean that the "required" attribute in the corresponding P3P policy must be set to "always", "opt-in" and "opt-out" respectively.

The corresponding associations among P3P recipients and compact policy codes follow:

4.2.7 Compact RETENTION

Information in the RETENTION element is represented in compact policies as follows:

4.2.8 Compact CATEGORIES

Note that if a P3P policy specifies one or more other-category in its full P3P policy, a single OTC token is used to signal the user agent that other-category's exist in the full P3P policy.

4.2.9 Compact TEST

4.2.10 Compact STATEMENT

The STATEMENT element is represented in compact policies using the curly brace { } symbols. The { represents the opening STATEMENT tag and the } represents the closing statement tag.

The syntax of the compact statement corresponds to the syntax of the full statement. Unless it surrounds a compact NON-IDENTIFIABLE element, each pair of braces MUST surround one compact RETENTION element and at least one of each of the following compact elements: PURPOSE, RECIPIENT, and CATEGORIES. Alternatively, a pair of braces may surround a compact NON-IDENTIFIABLE element; optionally any of the PURPOSE, RECIPIENT, and CATEGORIES elements; and optionally a RETENTION element.

A compact policy that has an improperly matching pair of curly braces or is missing one of the required statement elements MUST be treated as if no curly braces are present.

A compact policy may contain one or more statements. A compact policy with no {} elements is considered to have a single implied statement element.

4.3 Compact Policy Scope

When a P3P compact policy is included in a HTTP response header, it applies to cookies set by the current response. This includes cookies set through the use of a HTTP SET-COOKIE header or cookies set by script.

4.4 Compact Policy Lifetime

To use compact policies, the validity of the full P3P policy must span the lifetime of the cookie. There is no method to indicate that policy is valid beyond the life of the cookie because the value of user agent caching is marginal, since sites would not know when to optimize by not sending the compact policy. When a server sends a compact policy, it is asserting that the compact policy and corresponding full P3P policy will be in effect for at least the lifetime of the cookie to which it applies.

4.5 Transforming a P3P Policy to a Compact Policy

When using P3P compact policies, the Web site is responsible for building a compact policy by summarizing the policy referenced by the COOKIE-INCLUDE elements of a P3P policwoesy reference file. If a site's policy reference file uses COOKIE-EXCLUDE elements then the site will need to manage sending the correct P3P compact policies to the user agent given the cookies set in a specific response.

The transformation of a P3P policy to a P3P compact policy may result in a loss of descriptive policy information -- the compact policy may not contain all of the policy information specified in the full P3P policy. The information from the full policy that is discarded when building a compact policy includes expiry, data group/data-schema elements, entity elements, consequences elements, and disputes elements are reduced.

Full policies that include mandatory extensions MUST NOT be represented as compact policies.

The P3P 1.0 specification required that all purposes, recipients, and categories that appear in multiple statements in a full policy be aggregated in a compact policy, as described in section 3.3.1. With the addition of the compact STATEMENT element in P3P 1.1, this is no longer necessary, although it is still permitted. When performing the aggregation, a Web site MUST disclose all relevant tokens (for instance, observe Example 4.1, where multiple retention policies are specified.)

In addition, for each fixed category data element appearing in a statement the associated category as defined in the associated schema MUST be included in the compact policy.

The corresponding compact policy using the new compact grouping mechanism called compact-statement:

5. Data Schemas

5.1. Introduction

A data schema is a description of a set of allowed data types. P3P includes a way to describe data schemas so that services can communicate to user agents about the types of data they collect. A data schema is a hierarchical set of data types, which are specific classes of data a service might collect. Policies may specify data types to any level of specificifity. For a given data element chosen, if the policy does not specify which of the allowed subtypes may be collected, it must be assumed that ALL allowed subtypes are collected. Informally, the data schema is a hierarchy (represented in section base data structure) of data types. The more general the type you choose (the higher in the hierarchy), the more data types you are making statements about.

P3P 1.1. provides a new format for expressing P3P data schemas in a simpler and more standardized way than P3P 1.0. The new format uses Structures and Datatypes which can be validated against an XML schema.

5.1.1. Backward Compatibility Requirements

Backward compatibility with P3P1.0 is addressed as follows:

URI's of custom data schemas MUST be provided and referenced from policy instances, using both P3P 1.1 and P3P 1.0 compatible formats.

In practice, they may be authored using only the P3P1.1 format data elements and then a backward compatibile version can be created automatically using a XSLT P3P1.1 Schema backward compatibility transform. Using a server side XSLT P3P1.1 Schema backward compatibility transform it is even possible to publish just a P3P policy which references a dynamic transform of the P3P1.1 Data Schema, without publishing the P3P1.0 schema in static form. There is no guarantee however of the persistence of this service, therefore user agents SHOULD not use this service where P3P1.0 Data Schema validation is critical to the application.
Policy instances conforming to custom schemas written in the P3P 1.1 compatible format MUST include both new format data elements AND a translation of these elements into the P3P1.0 format. This requirement can easily be satisfied by writing policies including only P3P1.1 data elements, and then publishing them with the P3P Policy Data Element backward compatibility transform which transforms P3P1.1 data elements in the policy so they are readable by both P3P1.1 and P3P1.0 user agents. A P3P1.1 Data Element backward compatibility transform is available, which translates a policy with only P3P1.1 extension datatype elements into one with elements which may be validated by both P3P1.1 and P3P1.0 data schema formats.

In order that P3P 1.1 user agents do not have to be able to parse P3P1.0 data elements, ALL Policies conforming to P3P1.1 (including those just using Base Data Schema Elements) MUST publish policies with both P3P1.0 and P3P1.1 data element formats. It is anticipated that most policy authors will use a P3P1.1 policy editor which will output the correct formats automatically, however in the case that the policy is being written without a GUI, this can be easily acheived by writing policies using P3P1.1 data elements and publishing the P3P1.1 Data Element backward compatibility transform of your policy.

For Example, write the DATA-GROUP element as:

<DATA-GROUP
 base="http://www.p3pdstransformerservice.pl?schema=http:%2F%2Fwww.example.com%2Fcustomdataschema.xsd">
  <EXTENSION>
    <datatype xmlns="http://www.example.com/customdataschema.xsd">
      <dynamic>
        <clickstream>
          <CATEGORY>preference</CATEGORY>
        </clickstream>
      </dynamic>
    </datatype>
  </EXTENSION>
</DATA-GROUP>

and transform it to compliant format using the P3P1.1 Data Element backward compatibility transform to the following:

<DATA-GROUP
 base="http://www.p3pdstransformerservice.pl?schema=http:%2F%2Fwww.example.com%2Fcustomdataschema.xsd">
  <EXTENSION>
    <datatype xmlns="http://www.example.com/customdataschema.xsd">
      <dynamic>
        <clickstream>
        <CATEGORY>preference</CATEGORY>
        </clickstream>
      </dynamic>
    </datatype>
  </EXTENSION>
  <DATA ref="#dynamic.clickstream">
    <CATEGORIES>
      <preference/>
    </CATEGORIES>
  </DATA>
</DATA-GROUP>

A typical process of producing a policy with custom data elements may be summarized as follows.

For custom schemas:

Create and publish a custom data schema according to P3P1.1 specification.
Create policies using P3P1.1 data elements based on the schema created in 1.

Either:

Publish Backward compatibility transform of policy referencing P3P1.1 custom data schema and Dynamic transform of P3P1.1 data schema
E.g.

<DATA-GROUP
 base="http://www.p3pdstransformerservice.pl?schema=http:%2F%2Fwww.example.com%2Fcustomdataschema.xsd">
  <EXTENSION>
    <datatype xmlns="http://www.example.com/customdataschema.xsd">
      <classicalmusicpreference>
        <baroquemusicpreference/>
      </classicalmusicpreference>
    </datatype>
  </EXTENSION>
  <DATA ref="#classicalmusicpreference.baroquemusicpreference">
    <CATEGORIES>
      <preference/>
    </CATEGORIES>
  </DATA>
</DATA-GROUP>

or publish Backward compatibility transform of policy referencing P3P1.1 custom data schema and, using the P3P1.1 Schema backward compatibility transform a P3P1.0 version of the same schema published on policy author's server.
E.g.

<DATA-GROUP
 base="http://www.example.com/customdataschema.ds">
  <EXTENSION>
    <datatype xmlns="http://www.example.com/customdataschema.xsd">
      <classicalmusicpreference>
        <baroquemusicpreference/>
      </classicalmusicpreference>
    </datatype>
  </EXTENSION>
    <DATA ref="#classicalmusicpreference.baroquemusicpreference">
    <CATEGORIES>
      <preference/>
    </CATEGORIES>
  </DATA>
</DATA-GROUP>

Data elements can also be written in P3P1.0 format and transformed to the P3P1.1 format using P3P1.1 Data Element forward transform

5.1.2. P3P 1.1 Data Element Syntax Overview

The P3P 1.1 Data Schema is an XML schema which describes elements organized in a hierarchy of increasing specificity. Informally speaking, if you say you collect data type a, then you also say that you collect all its allowed subtypes, unless you specify which of the subtypes you collect, by inserting a child element.

For example

<datatype>
  <user/>
</datatype>

means: "we might collect any of the allowed subtypes of user data (name,birthdate,login, cert etc....) Furthermore this property is carried through to all the subtypes of these elements. So if you collect user data, you also collect login-id and login-password etc...

If instead one specifies

<datatype>
  <user>
    <cert>
      <key/>
    </cert>
  </user>
</datatype>

this means that one may only collect the user's certificate key and nothing else.

More formally speaking, for an element  to be defined as an allowed child of element <A> means if the policy states that it may collect data of type <A>, then it can also be taken to state that it may also collect data of type . The inverse relation however does not hold. Transitivity also holds for this relation. That is, if a policy states that it collects data of type <A> and if  is an allowed subelement of <A> and <C> is an allowed subelement of , then it can be assumed that the controller of the policy may also collect data of type <C>. The hierarchy is mirrored by the hierarchy of XML elements used to express them. It should be noted that the use of a particular data element is NOT a request for that particular type of data, or a statement that the data is collected, rather a hypothetical statement that it may be collected.

P3P has defined a default data schema called the P3P base data schema that includes a large number of data elements commonly used by services. Note that the data element names specified in the base data schema or in extension data schemas may be used for purposes other than P3P policies. For example, Web sites may use these names to label HTML form fields. By referring to data the same way in P3P policies and forms, automated form-filling tools can be better integrated with P3P user agents.

5.2. How to express data types in P3P Policies

5.2.1 Basics

The following is an example instance of a P3P1.1 compliant datatype element, full details of the data schema hierarchy are given in section 5.5.

<DATA-GROUP>
  <EXTENSION>
    <datatype optional="yes">
      <dynamic>
        <clickstream>
          <CATEGORY>preference</CATEGORY>
        </clickstream>
      </dynamic>
    </datatype>
  </EXTENSION>
  <DATA ref="#dynamic.clickstream">
          <CATEGORIES>preference</CATEGORIES>
  </DATA>
</DATA-GROUP>

This example shows the following aspects of how to use data elements in P3P 1.1:

Root is always an element named datatype.
optional indicates whether or not the site requires visitors to submit this data type in order to access a resource or complete a transaction; "no" indicates that the data element is not optional (it is required), while "yes" indicates that the data element is optional. The default is "no.".
Under this are nested elements describing the types of data that the P3P Statement is about. The hierarchy of these elements is described in detail in section 5.5 Structure of Base Data Schema
Greater levels of detail in the specification of a data type are expressed by using allowed children of a particular cdata type, according the the scheme expressed in the P3P 1.1 Data Schema. Nesting corresponds to increasing specificity of possible data collected, so for instance in the above example, the meaning of the data element is that the controller of the policy may collect data of type Dynamic, but only the subclass of Dynamic data which is also Clickstream data.
Natural language descriptors of the meaning of these elements are found in the Data Schema and therefore should not be included in policy instances. The human readable descriptor corresponds to an XSD comment beneath the element it refers to, of format:
```
<annotation>
 <documentation>
 This element can describe the capture of
 HTTP Protocol Information such as header values
 </documentation>
 <appinfo>
 HTTP Protocol Information
 </appinfo>
</annotation>
 
```
User agents SHOULD use these descriptors when rendering data types in human readable format (for example in a human readable translation of a P3P policy).
Most data elements have categories assigned to them when they are defined in a data schema. See 5.2.2 Categories for more information on categories.

5.2.2 Categories in P3P Data Schemas

Categories may be assigned at the lowest level of a data type definition. Categories are a way of giving a meaning to types of data which may be too general to be useful in a policy. For example cookie data may contain any kind of information and it is therefore useful to be able to describe whether the cookie data is demographic, navigation etc... Another example is clickstream data, which may be delimited as navigation, computer or demographic type clickstream data.

In this capacity as broad types for unspecific data such as cookies, categories can only be assigned as a leaf child (with only other category siblings) of the hierarchy.

For example the following is correct syntax.

<datatype>
  <dynamic>
    <cookies>
      <CATEGORY>preference</CATEGORY>
    </cookies>
  </dynamic>
</datatype>

Whereas the following is not:

<datatype>
  <dynamic>
    <cookies/>
    <CATEGORY>preference</CATEGORY>
  </dynamic>
</datatype>

Categories are simply appended to the lowest level of the hierarchy specified. Most of the elements in the base data schema are so called "fixed"data elements: they belong to one or at most two category classes. By assigning a category invariably to elements or structures in the base data schema, services and users are able to refer to entire groups of elements simply by referencing the corresponding category. For example, using [APPEL], the privacy preferences exchange language, users can write rules that warn them when they visit a site that collects any data element in a certain category.

If an element is assigned to multiple categories, multiple elements referencing the appropriate categories can be used. For example, the following piece of XML can be used to declare that the data elements in user -> name have both category "physical" and "demographic":

<datatype>
  <dynamic>
    <cookies>
      <CATEGORY>preference</CATEGORY>
      <CATEGORY>demographic</CATEGORY>
    </cookies>
  </dynamic>
</datatype>

Please note that the category classes of data elements/structures can not be overridden, for example by writing policies that assign a different category to a known fixed base data element. User agents MUST ignore such categories and instead use the original category (or set of categories) listed in the schema definition. User agents MAY preferably alert the user that a fixed data element is used together with a non-standard category class.

Note that except in the case of Variable-Category Data Elements, it is not mandatory to specify the category of a data element. If the category of the element is not specified, then User Agents assume that data of all categories allowed in the Base Data Schema may be collected.

5.2.3 Variable-Category Data Elements

Some elements in the base data schema have a special status which requires that a category MUST be specified when using these elements in the policy. These are the called Dynamic Category elements, because they may be in any of the allowed categories for the base data schema. Because they are not initially assigned to any specific category, it is required that the policy writer specify which category or categories they belong to in order to give them meaning. The two most important such elements are cookie data and dynamicmiscdata

Variable category elements are distinguished by the fact that the schema defining them assigns them to all possible categories in the category data type. Furthermore, a minOccurs attribute with value 1 specifies that at least one must be specified. For example when specifying the "cookies" Data Element, which can take various categories depending on the situation (e.g. when used for a credit card expiration date vs. for a birth date), the following schema definition can be used:

<xsd:element name="miscdata">
  <xsd:annotation>
    <xsd:documentation>
      Miscellaneous Non-base Data Schema = information
    </xsd:documentation>
  </xsd:annotation>
  <xsd:complexType mixed="true">
    <xsd:sequence minOccurs="1">
      <xsd:element name="CATEGORY" minOccurs="0" maxOccurs="unbounded" type="allCategories" />
    </xsd:sequence>
  </xsd:complexType>
</xsd:element>

5.2.4 Referencing External Schemas

External schemas may reference elements in other schemas simply by referring to another namespace. For example

<schema targetNamespace='http://www.example.com/Report'
 xmlns:p3pBDS='http://www.w3.org/2004/02/P3Pv11'>
  <xs:element name="creditCard">
    <xs:element ref="p3pBDS:date"/>
  </xs:element>
</schema>

But note that in contrast to the P3P 1.0 data schema format, it is not possible to alter the category assignations of reused elements. If this is required, they must be redefined. Schema extensions may still reference elements in other schemas (e.g. reuse of date element), but they may not assign a category (you cannot change the properties of a referenced element within XSD)]

Note that while user preferences can list such variable data elements without any additional category information (effectively expressing preferences over any usage of this element), services MUST always explicitly specify the categories that apply to the usage of a variable data element in their particular policy. This information has to appear as a category element in the corresponding DATA element listed in the policy, for example as in:

<datatype>
  <dynamic>
    <cookies>
      <CATEGORY>uniqueid</CATEGORY>
    </cookies>
  </dynamic>
</datatype>

where a service declares that cookies are used to recognize the user at this site (i.e. category Unique Identifiers).

If a service wants to declare that a data element is in multiple categories, it simply declares the corresponding categories as in:

<datatype>
  <dynamic>
    <cookies>
      <CATEGORY>
        preference
      </CATEGORY>
      <CATEGORY>
        uniqueid
      </CATEGORY>
    </cookies>
  </dynamic>
</datatype>

With the above declaration a service announces that it uses cookies both to recognize the user at this site and for storing user preference data. Note that for the purpose of P3P there is no difference whether this information is stored in two separate cookies or in a single one.

Finally, note when writing new schemas that categories must be upward inherited. That is, if a data type is in a certain category then any broader data types that it is a member of, are also in this category. For example if URI may collect data in the category online, then User may also collect data in the category online. Therefore, we suggest to schema authors that they do their best to insure that all applicable categories are applied to new data elements they create.

5.2.5 Natural Language description of data elements

Natural language descriptions of the meaning of data elements may be found within <annotation> children of the element definition in the base data schema. These may be of 2 kinds:

<description>: a long description for documentation purposes

<appinfo>: a short description for display in data capture summaries.

These descriptions are intended to be used by user-agents in creating translations to human readable policies. They should not however be included in machine readable policies.

5.3 Defining new Schemas

Services may declare new data elements by creating and publishing their own data schemas expressed using XSD. These schemas must also comply with certain rules over and above the rules of correct XSD syntax. This section describes the rules for creating these schemas. These new data schemas are then referred to simply using the xmlns attribute for the elements below the datatype element.

There are 3 important points when creating new custom XSD data schemas. New custom schemas :

Must follow a hierarchy of increasing specificity
Must declare a global category xsd datatype and assign a restriction on this type (i.e. a set of allowed categories) for each data element declared
May annotate elements with human readable descriptions using the description and appinfo elements of XSD

5.3.1 Allowed Structure of custom XSD Schemas

New schemas can be defined using the XML Schema Definition language [Add Link], they must follow the following rules:

As with the P3P Base Data Schema, datatype sub-elements must be organized into a hierarchy of increasing specificity. For an element  to be defined as an allowed child of element <A> signifies that an entity which might collect <A>, unless otherwise specified, might also collect data of type . The inverse relation however does not hold. Transitivity also holds for this relation. That is, if a policy states that Entity eXample may collect data of type <A> and  is an allowed subelement of <A> and <C> is an allowed subelement of , then it can be assumed that Entity eXample may collect data of type <C>. For example <classicalmusicpreference> would be defined as an allowed subelement of <musicalpreference>, meaning that if in a policy the data type is defined as

<datatype>
  <musicalpreference/>
</datatype>

then it can be assumed that the policy is describing the possible collection of data of classical music preference data.

The relationships are also transitive, so <baroquemusicpreference> is understood to be a subclass of <musicalpreference> because it is a subelement of <classicalmusicpreference> which is a subelement of <musicalpreference>

This could be expressed in the following XML Schema:

<element minoccurs="0" maxoccurs="1" name="musical-preference">
  <element minoccurs="0" maxoccurs="1" ref="classicalmusic-preference"/>
    <annotation>
      <documentation>
        Musical Preferences
      </documentation>
    </annotation>
    <element ref="CATEGORY" minoccurs="0" maxoccurs="*" type="allCategories"/>
  </element>

  <element minoccurs="0" maxoccurs="1" name="classicalmusic-preference">
    <annotation>
      <documentation>
        Classical Musical Preferences
      </documentation>
    </annotation>
    <element minoccurs="0" maxoccurs="1" ref="baroquemusic-preference"/>
  </element>

  <element minoccurs="0" maxoccurs="1"
  name="baroquemusic-preference">
    <annotation>
      <documentation>
        Classical Musical Preferences
      </documentation>
    </annotation>
</element>

5.3.2 Defining categories in custom schemas.

Categories may be assigned at any level of the XML hierarchy
At least one category must be defined for each element defined.
Possible categories must be declared as an xsd datatype
To declare that any category may be used, just use the following syntax (the minOccurs=1 defines the fact that at least one category must be specified):
```
<xsd:sequence minOccurs="1">
 <xsd:element
 name="CATEGORY" minOccurs="0" maxOccurs="unbounded"
 type="allCategories" />
</xsd:sequence>
```
Categories must follow a bubble-up rule in that any categories assigned to a lower level element must also be assigned to any of its ancestors. This mirrors the semantics of the may-include-elements of class relation which describes the P3P Data Schema. If <datatype> A may include <datatype> B and Category A may include <datatype> B, then Category A may include <datatype> A.
Categories must be defined as restrictions on a global <datatype> for the schema which is defined as a root level element. For example in the BDS, the following element is defined:

<simpleType name="allCategories">
  <restriction base="xs:string">

    <enumeration value="uniqueid">
    </enumeration>

    <enumeration value="demographic">
    </enumeration>

    <enumeration value="physical">
    </enumeration>

    <enumeration value="online">
    </enumeration>

    <enumeration value="computer">
    </enumeration>

    <enumeration value="navigation">
    </enumeration>

    <enumeration value="interactive">
    </enumeration>

  </restriction>
</simpleType>

Definition of allowed categories for a particular datatype are then taken as restrictions of this basic data type - for example:

<element name="CATEGORY" minoccurs="0" maxoccurs="*">
  <simpleType>
    <restriction base="allCategories">
      <pattern value="computer" />
    </restriction>
  </simpleType>
</element>

Note that this must be placed as a leaf node in the hierarchy (i.e. it should have no children) and it must only have category siblings.

5.3.3 Natural Language Annotations in Custom Data Schemas

P3P data typing XSD's alllow two annotation fields for natural language description. Below each element description, schema creators MAY place an xsd:annotation element with the following child elements:

<description>: a long description for documentation purposes

<appinfo>: a short description for display in policy summaries.

Services publishing a data schema MAY wish to translate these fields into multiple languages. The annotation element's contents MAY be translated, but the element name MUST NOT be translated - this field needs to stay constant across translations of a data schema.

If a service is going to provide a data schema in multiple natural languages, then it SHOULD examine the Accept-Language HTTP request-header on requests for that data schema to pick the best available alternative.

5.4 Persistence of data schemas

An essential requirement on data schemas is the persistence of data schemas: data schemas that can be fetched at a certain URI can only be changed by extending the data schema in a backward-compatible way (that is to say, changing the data schema does not change the meaning of any policy using that schema). This way, the URI of a policy acts in a sense like a unique identifier for the data elements and structures contained therein: any data schema that is not backward-compatible must therefore use a new different URI.

Note that a useful application of the persistence of data schemas is given for example in the case of multi-lingual sites: multiple language versions (translations) of the same data schema can be offered by the server, using the HTTP "Content-Language" response header field to properly indicate that a particular language has been used for the data schema.

5.5 Structure of Base Data Schema

The XML schema is not designed to be human readable, but in writing policies, and choosing data elements to make statements about, it can be useful to have a picture of the hierarchy of categories available. Section 5.5.1. gives a visual overview of the data schema hierarchy which is intended to be used as a quick reference. Section 5.5.2. lists elements with their exact definitions and their allowed children. It does not show the allowed categories, which are described in section 5.5.2.

All P3P-compliant user agent implementations MUST be aware of the Base Data Schema.

5.5.1 Visual overview of the base data schema hierarchy

5.5.1.1 Dynamic Data

  dynamic
    ├clickstream
    │  ├uri
    │  │  ├authority
    │  │  ├stem
    │  │  └querystring
    │  ├timestamp
    │  │  ├ymd.year
    │  │  ├ymd.month
    │  │  ├ymd.day
    │  │  ├hms.hour
    │  │  ├hms.minute
    │  │  ├hms.second
    │  │  ├fractionsecond
    │  │  └timezone
    │  ├clientip
    │  │  ├hostname
    │  │  ├partialhostname
    │  │  ├fullip
    │  │  └partialip
    │  ├other.httpmethod
    │  ├other.bytes
    │  └other.statuscode
    ├http
    │  ├referer
    │  │  ├authority
    │  │  ├stem
    │  │  └querystring
    │  └useragent
    ├clientevents
    ├cookies
    ├searchtext
    ├interactionrecord
    └miscdata

5.5.1.2 User Data

user
  ├name
  │  ├prefix
  │  ├given
  │  ├middle
  │  ├family
  │  ├suffix
  │  └nickname
  ├bdate
  │  ├ymd.year
  │  ├ymd.month
  │  ├ymd.day
  │  ├hms.hour
  │  ├hms.minute
  │  ├hms.second
  │  ├fractionsecond
  │  └timezone
  ├login
  │  ├id
  │  └password
  ├cert
  │  ├key
  │  └format
  ├gender
  ├jobtitle
  ├home-info
  │  ├postal
  │  │  ├name
  │  │  │  ├prefix
  │  │  │  ├given
  │  │  │  ├middle
  │  │  │  ├family
  │  │  │  ├suffix
  │  │  │  └nickname
  │  │  ├street
  │  │  ├city
  │  │  ├stateprov
  │  │  ├postalcode
  │  │  ├organization
  │  │  └country
  │  ├telecom
  │  │  ├telephone
  │  │  │  ├intcode
  │  │  │  ◁loccode
  │  │  │  ├number
  │  │  │  ├ext
  │  │  │  └comment
  │  │  ├fax
  │  │  │  ├intcode
  │  │  │  ├loccode
  │  │  │  ├number
  │  │  │  ├ext
  │  │  │  └comment
  │  │  ├mobile
  │  │  │  ├intcode
  │  │  │  ├loccode
  │  │  │  ├number
  │  │  │  ├ext
  │  │  │  └comment
  │  │  └pager
  │  │    ├intcode
  │  │    ├loccode
  │  │    ├number
  │  │    ├ext
  │  │    └comment
  │  └online
  │    ├email
  │    └uri
  └business-info
    ├postal
    │  ├name
    │  │  prefix
    │  │  given
    │  │  middle
    │  │  family
    │  │  suffix
    │  │  nickname
    │  │street
    │  │city
    │  │stateprov
    │  │postalcode
    │  │organization
    │  │country
    │telecom
    │  ├telephone
    │  │  ├intcode
    │  │  ├loccode
    │  │  ├number
    │  │  ├ext
    │  │  └comment
    │  ├fax
    │  │  ├intcode
    │  │  ├loccode
    │  │  ├number
    │  │  ├ext
    │  │  └comment
    │  ├mobile
    │  │  ├intcode
    │  │  ├loccode
    │  │  ├number
    │  │  ├ext
    │  │  └comment
    │  └pager
    │    ├intcode
    │    ├loccode
    │    ├number
    │    ├ext
    │    └comment
    │online
    │  ├email
    │  └uri
    ├employer
    └department

5.5.1.3 Third Party Data

thirdparty
  ├name
  │  ├prefix
  │  ├given
  │  ├middle
  │  ├family
  │  ├suffix
  │  └nickname
  ├bdate
  │  ├ymd.year
  │  ├ymd.month
  │  ├ymd.day
  │  ├hms.hour
  │  ├hms.minute
  │  ├hms.second
  │  ├fractionsecond
  │  └timezone
  ├login
  │  ├id
  │  └password
  ├cert
  │  ├key
  │  └format
  ├gender
  ├jobtitle
  ├home-info
  │  ├postal
  │  │  ├name
  │  │  │  ├prefix
  │  │  │  ├given
  │  │  │  ├middle
  │  │  │  ├family
  │  │  │  ├suffix
  │  │  │  └nickname
  │  │  ├street
  │  │  ├city
  │  │  ├stateprov
  │  │  ├postalcode
  │  │  ├organization
  │  │  └country
  │  ├telecom
  │  │  ├telephone
  │  │  │  ├intcode
  │  │  │  ├loccode
  │  │  │  ├number
  │  │  │  ├ext
  │  │  │  └comment
  │  │  ├fax
  │  │  │  ├intcode
  │  │  │  ├loccode
  │  │  │  ├number
  │  │  │  ├ext
  │  │  │  └comment
  │  │  ├mobile
  │  │  │  ├intcode
  │  │  │  ├loccode
  │  │  │  ├number
  │  │  │  ├ext
  │  │  │  └comment
  │  │  ├pager
  │  │    ├intcode
  │  │    ├loccode
  │  │    ├number
  │  │    ├ext
  │  │    └comment
  │  ├online
  │    ┒email
  │    └uri
  └business-info
      │postal
      │  │name
      │  │  │prefix
      │  │  │given
      │  │  │middle
      │  │  │family
      │  │  │suffix
      │  │  │nickname
      │  │street
      │  │city
      │  │stateprov
      │  │postalcode
      │  │organization
      │  │country
      │telecom
      │  ├telephone
      │  │  │intcode
      │  │  │loccode
      │  │  │number
      │  │  │ext
      │  │  │comment
      │  ├fax
      │  │  │intcode
      │  │  │loccode
      │  │  │number
      │  │  │ext
      │  │  │comment
      │  ├mobile
      │  │  ├intcode
      │  │  ├loccode
      │  │  ├number
      │  │  ├ext
      │  │  └comment
      │  └pager
      │    ├intcode
      │    ├loccode
      │    ├number
      │    ├ext
      │    └comment
      ├online
      │  ├email
      │  └uri
      ├employer
      └department

5.5.1.4 Business Data

business
  ├name
  │department
  ├cert
  │  ├key
  │  └format
  └contact-info
    ├postal
    │  ├name
    │  │  ├prefix
    │  │  ├given
    │  │  ├middle
    │  │  ├family
    │  │  ├suffix
    │  │  └nickname
    │  ├street
    │  ├city
    │  ├stateprov
    │  ├postalcode
    │  ├organization
    │  └country
    └telecom
      ├telephone
      │  ├intcode
      │  ├loccode
      │  ├number
      │  ├ext
      │  └comment
      ├fax
      │  ├intcode
      │  ├loccode
      │  ├number
      │  ├ext
      │  └comment
      ├mobile
      │  ├intcode
      │  ├loccode
      │  ├number
      │  ├ext
      │  └comment
      ├pager
      │  ├intcode
      │  ├loccode
      │  ├number
      │  ├ext
      │  └comment
      └online
        ├email
        └uri

5.5.2. Data Schema Element Details

The Table below defines the details of the data schema elements. Although it is a flat list, it does define the hierarchy by defining the allowed subtypes of each class. The following tables are mainly for referencing the exact description of the meaning of each data type and the allowed categories. More than one category may be associated with a fixed data element. However, each base data element is assigned to only one category whenever possible. Data schema designers are recommended to do the same. To choose an element from the hierarchy, you should refer to the tables in section 5.5.1.

5.6. Using Data Elements

P3P offers Web sites a lot of flexibility in how they describe the types of data they collect.

Type	Allowed Categories	Allowed Descendents	Short Description	Notes
Dynamic	Variable	clickstream ,http, clientevents, cookies, searchtext, interactionrecord, miscdata	Dynamic Data	In some cases, there is a need to specify data elements that do not have fixed values that a user might type in or store in a repository. In the P3P base data schema, all such elements are grouped under the class of dynamic data. Sites may refer to the types of data they collect using the dynamic data set only, rather than enumerating all of the specific data elements.
User	Physical Contact Information, Demographic and Socioeconomic Data, Unique Identifiers,Online Contact Information	name, bdate, login, cert, gender, jobtitle, home-info, business-info	General information about the user
Third-party	Physical Contact Information, Demographic and Socioeconomic Data, Unique Identifiers,Online Contact Information	name, bdate, login, cert, gender, jobtitle, home-info, business-info		The thirdparty data set allows users and businesses to provide values for a related third party. This can be useful whenever third party information needs to be exchanged, for example when ordering a present online that should be sent to another person, or when providing information about one's spouse or business partner. Such information could be stored in a user repository alongside the user data set. User agents may offer to store multiple such thirdparty data sets and allow users to select the appropriate values from a list when necessary. The allowed subtypes of thirdparty data element are identical to those of the user data set.
Business		name, department, cert, contact-info		The business data type features a subset of user data relevant for describing legal entities. In P3P1.1, this data element is primarily used for describing the policy entity, although it should also be applicable to business-to-business interactions.
name	Physical Contact Information, Demographic and Socioeconomic Data	prefix, given, family, middle, suffix, nickname	User's Name
bdate	Demographic and Socioeconomic Data	ymd.year, ymd.month, ymd.day, hms.hour, hms.minute, hms.second, fractionsecond, timezone	User's Birth Date
login	Unique Identifiers	id,password	User's Login Information	The login element and its children refer to information (IDs and passwords) for computer systems and Web sites which require authentication. Note that this data element should not be used for computer systems or Web sites which use digital certificates for authentication: in those cases, the cert element should be used.
cert	Unique Identifiers	key, format	User's Identity Certificate	The cert element and its children refer to identity certificates (like, for example, X.509).
gender	Demographic and Socioeconomic Data	-	User's Gender (Male or Female)
employer	Demographic and Socioeconomic Data	-	User's Employer
department	Demographic and Socioeconomic Data	-	Department or Division of Organization where User is Employed
jobtitle	Demographic and Socioeconomic Data	-	User's Job Title
home-info	Physical Contact Information, Online Contact Information, Demographic and Socioeconomic Data	postal, telecom, online	User's Home Contact Information
contact-info	Physical Contact Information, Online Contact Information, Demographic and Socioeconomic Data	postal, telecom, online	Contact Information for the Organization
business-info	Physical Contact Information, Online Contact Information, Demographic and Socioeconomic Data	postal, telecom, online, employer, department	User's Business Contact Information
clickstream	Navigation and Click-stream Data, Computer Information	uri, timestamp, clientip, other.httpmethod, other.bytes, other.statuscode	Click-stream Information	The clickstream element and its children refer to information typically stored in Web-server access logs. The clickstream element is expected to apply to practically all Web sites. It represents the combination of information typically found in Web server access logs: the IP address or hostname of the user's computer, the URI of the resource requested, the time the request was made, the HTTP method used in the request, the size of the response, and the HTTP status code in the response. Web sites that collect standard server access logs as well as sites which do URI path analysis can use this data element to describe how that data will be used. Web sites that collect only some of the data elements listed as allowed children of the clickstream element MAY choose to list those specific elements rather than the entire dynamic-clickstream element. This allows sites with more limited data-collection practices to accurately present those practices to their visitors. The resource in the HTTP request is captured by the uri field. The IP address of the client system making the request is given by the clientip field.
http	Navigation and Click-stream Data, Computer Information	referer, useragent	HTTP Protocol Information	The http element contains additional information contained in the HTTP protocol. The http element and its children refer to information carried by the HTTP protocol which is not covered by the clickstream element and its children.
clientevents	Navigation and Click-stream Data	-	User's Interaction with a Resource	The clientevents element represents data about how the user interacts with their Web browser while interacting with a resource. For example, an application may wish to collect information about whether the user moved their mouse over a certain image on a page, or whether the user ever brought up the help window in a Java applet. This kind of information is represented by the clientevents data element. Much of this interaction record is represented by the events and data defined by the Document Object Model (DOM) Level 2 Events [DOM2-Events]. The clientevents data element also covers any other data regarding the user's interaction with their browser while the browser is displaying a resource. The exception is events which are covered by other elements in the base data schema. For example, requesting a page by clicking on a link is part of the user's interaction with their browser while viewing a page, but merely collecting the URL the user has clicked on does not require declaring this data element; clickstream covers that event. However, the DOM event DOMFocusIn (representing the user moving their mouse over an object on a page) is not covered by any other existing element, so if a site is collecting the occurrence of this event, then it needs to state that it collects the dynamic.clientevents element. Items covered by this data element are typically collected by client-side scripting languages, such as JavaScript, or by client-side applets, such as ActiveX or Java applets. Note that while the previous discussion has been in terms of a user viewing a resource, this data element also applies to Web applications which do not display resources visually - for example, audio-based Web browsers.
cookies	variable-category	-	Use of HTTP Cookies	The cookies element should be used whenever HTTP cookies are set or retrieved by a site. Please note that cookies is a variable category data element and requires the explicit declaration of usage categories in a policy.
miscdata	variable-category	-	Miscellaneous Non-base Data Schema Information	The miscdata element references information collected by the service that the service does not reference using a specific data element. Categories have to be used to better describe these data: sites MUST reference a separate miscdata element in their policies for each category of miscellaneous data they collect.
searchtext	Interactive Data	-	Search Terms	The searchtext element references a specific type of solicitation used for searching and indexing sites. For example, if the only fields on a search engine page are search fields, the site only needs to disclose that data element.
interactionrecord	Interactive Data	-	Server Stores the Transaction History	The interactionrecord element should be used if the server is keeping track of the interaction it has with the user (i.e. information other than clickstream data, for example account transactions, etc).
ymd.year	variable-category	-	Year	The following elements refer to data connected with dates. Since date information can be used in different ways, depending on the context, all such information is tagged as being of variable category. For example, schema definitions can explicitly set the corresponding category in the element referencing these elements, where soliciting the birthday of a user might be "Demographic and Socioeconomic Data", while the expiration date of a credit card might belong to the `Purchase Information` category.
ymd.month	variable-category	-	Month
ymd.day	variable-category	-	Day
hms.hour	variable-category	-	Hour
hms.minute	variable-category	-	Minute
hms.second	variable-category	-	Second
fractionsecond	variable-category	-	Fraction of Second
timezone	variable-category	-	Time Zone
prefix	Demographic and Socioeconomic Data	-	Name Prefix
given	Physical Contact Information	-	Given Name (First Name)
family	Physical Contact Information	-	Family Name (Last Name)
middle	Physical Contact Information	-	Middle Name
suffix	Demographic and Socioeconomic Data	-	Name Suffix
nickname	Demographic and Socioeconomic Data	-	Nickname
id	Unique Identifiers	-	Login ID	The "id" element represents the ID portion of the login information for a computer system. Often, user IDs are made public, while passwords are kept secret. IDs do not include any type of biometric authentication mechanisms.
password	Unique Identifiers	-	Login Password	The "password" element represents the password portion of the login information for a computer system. This is a secret data value, usually a character string, that is used in authenticating a user. Passwords are typically kept secret, and are generally considered to be sensitive information
key	Unique Identifiers	-	Certificate Key
format	Unique Identifiers	-	Certificate Format	The "format" element is used to represent the information of an IANA registered public key or authentication certificate format, while the "key" field is used to represent the corresponding certificate key.
postal	Physical Contact Information, Demographic and Socioeconomic Data	name, street, city, stateprov, postalcode, organization, country	Postal Address Information	The following 3 elements and their children refer to contact information. Services can specify precisely which set of data they need, postal, telecommunication, or online address information. The postal element and its children refer to a postal mailing address.
telecom	Physical Contact Information	telephone, fax, mobile, pager	Telecommunications Information	The telecom element and its children refer to the characteristics of telephone, fax, mobile and pager numbers.
online	Online Contact Information	email,uri	Online Address Information	The online element and its children refer to online information about a person or legal entity.
intcode	Physical Contact Information	-	International Telephone Code
loccode	Physical Contact Information	-	Local Telephone Area Code
number	Physical Contact Information	-	Telephone Number
ext	Physical Contact Information	-	Telephone Extension
comment	Physical Contact Information	-	Telephone Optional Comments
street	Physical Contact Information	-	Street Address
city	Demographic and Socioeconomic Data	-	City
stateprov	Demographic and Socioeconomic Data	-	State or Province
postalcode	Demographic and Socioeconomic Data	-	Postal Code
country	Demographic and Socioeconomic Data	-	Country Name	The "country" element represents the information of the name of the country (for example, one among the countries listed in [ISO3166]).
organization	Demographic and Socioeconomic Data	-	Organization Name
telephone	Physical Contact Information	intcode, loccode, number, ext, comment	Telephone Number
fax	Physical Contact Information	intcode, loccode, number, ext, comment	Fax Number
mobile	Physical Contact Information	intcode, loccode, number, ext, comment	Mobile Telephone Number
pager	Physical Contact Information	intcode, loccode, number, ext, comment	Pager Number
email	Online Contact Information	-	Email Address
uri	Online Contact Information	-	Home Page Address	The uri element and its children refer to Universal Resource Identifiers (URI), which are defined in [URI]. Since URI information can be used in different ways, depending on the context, all the child elements of the uri element are tagged as being of variable category. Schema definitions MUST explicitly set the corresponding category in the element referencing this data structure.
authority	variable-category	-	URI Authority
stem	variable-category	-	URI Stem
querystring	variable-category	-	Query-string Portion of URI
authority	variable-category	-	URI Authority	The authority of a URI is defined as the authority component in [URI]. The stem of a URI is defined as the information contained in the portion of the URI after the authority and up to (and including) the first '?' character in the URI, and the querystring is the information contained in the portion of the URI after the first '?' character. For URIs which do not contain a '?' character, the stem is the entire URI, and the querystring is empty.
stem	variable-category	-	URI Stem
querystring	variable-category	-	Query-string Portion of URI
hostname	Computer Information	-	Complete Host and Domain Name	The `hostname` element is used to represent collection of either the simple hostname of a system, or the full hostname including domain name. The `partialhostname` element represents the information of a fully-qualified hostname which has had at least the host portion removed from the hostname. In other words, everything up to the first '.' in the fully-qualified hostname MUST be removed for an address to quality as a "partial hostname".
partialhostname	Demographic	-	Partial Hostname
fullip	Computer Information	-	Full IP Address	The `fullip` element represents the information of a full IP version 4 or IP version 6 address. The `partialip` element represents an IP version 4 address (only - not a version 6 address) which has had at least the last 7 bits of information removed. This removal MUST be done by replacing those bits with a fixed pattern for all visitors (for example, all 0's or all 1's). Certain Web sites are known to make use not of the visitor's entire IP address or hostname, but rather make use of a reduced form of that information. By collecting only a subset of the address information, the site visitor is given some measure of anonymity. It is certainly not the intent of this specification to claim that these "stripped" IP addresses or hostnames are impossible to associate with an individual user, but rather that it is significantly more difficult to do so. Sites which perform this data reduction MAY wish to declare this practice in order to more-accurately reflect their practices.
partialip	Demographic	-	Partial IP Address
uri	Navigation and click-stream data	authority, stem, querystring	URI of Requested Resource
timestamp	Navigation and click-stream data	ymd.year, ymd.month, ymd.day, hms.hour, hms.minute, hms.second, fractionsecond, timezone	Request Timestamp	The time at which the server processes the request is represented by the timestamp field. Server implementations are free to define this field as the time the request was received, the time that the server began sending the response, the time that sending the response was complete, or some other convenient representation of the time the request was processed.
clientip	Computer Information, Demographic and Socioeconomic Data	hostname, partialhostname, fullip, partialip	Client's IP Address or Hostname	The clientip element and its children refer to IP addresses and Domain Name System (DNS) hostnames.
other.httpmethod	Navigation and click-stream data	-	HTTP Request Method	The `HTTP method` (such as GET, POST, etc) in the client's request
other.bytes	Navigation and click-stream data	-	Number of Data Bytes in Response	The number of bytes in the response-body sent by the server
other.statuscode	Navigation and click-stream data	-	Response Status Code	The HTTP status code on the request, such as `200, 302, or 404` (see section 6.1.1 of [`HTTP1.1`] for details).
referer	Navigation and click-stream data	authority, stem, querystring	Last URI Requested by the User	The referer element represents the information in the HTTP Referer header, which gives information about the previous page visited by the user. Note that this field is misspelled in exactly the same way as the corresponding HTTP header
useragent	Computer Information	-	User Agent Information	The useragent field represents the information in the HTTP User-Agent header (which gives information about the type and version of the user's Web browser), and/or the HTTP accept* headers.

By using the

<
dynamic><miscdata/></dynamic>

element, sites can specify the types of data they collect without having to enumerate every individual data element. This may be convenient for sites that collect a lot of data or sites belonging to large organizations that want to offer a single P3P policy covering the entire organization. However, the disadvantage of this approach is that user agents will have to assume that the site might collect any data element belonging to the categories referenced by the site. So, for example, if a site's policy states that it collects <dynamic><miscdata/></dynamic> of the physical contact information category, but the only physical contact information it collects is business address, user agents will nonetheless assume that the site might also collect telephone numbers. If the site wishes to be clear that it does not collect telephone numbers or any other physical contact information other than business address, than it should disclose that it collects

<user><business-info><contact><postal/>
</contact></business-info></user>

. Furthermore, as user agents are developed with automatic form-filling capabilities, it is likely that sites that enumerate the data they collect will be able to better integrate with these tools.

By defining new data schemas, sites can precisely specify the data they collect beyond the base data set. However, if user agents are unfamiliar with the elements defined in these schemas, they will be able to provide only minimal information to the user about these new elements. The information they provide will be based on the category and display names specified for each element.

Regardless of whether a site wishes to make general or specific data disclosures, there are additional advantages to disclosing specific elements from the <dynamic/>data set. For example, by disclosing <dynamic><cookies/></dynamic> a site can indicate that it uses cookies and explain the purpose of this use. User agent implementations that offer users cookie control interfaces based on this information are encouraged. Likewise, user agents that by default do not send the HTTP_REFERER header, might look for the <dynamic><http><referrer/></http></dynamic> element in P3P policies and send the header if it will be used for a purpose the user finds acceptable.

5.7. Semantics of P3P Data Schemas

XML does not define a formal semantics except when used within RDF. The use of XSD to define classes of data types however necessarily implies a correspondence between XML elements and real-world classes of data, which is therefore a form of semantics. We have chosen not to use a language with formal semantics because of the sparse support for such languages as RDF and OWL in commercial browser implementations. A translation of P3P including the data schema into RDF and OWL can be found at [UPDATE].

6.0 User Agent Guidelines

This section specifies guidelines for P3P 1.1 user agents. Some of these guidelines serve to reinforce requirements that appear elsewhere in this specification, providing specific guidance for user agent implementers. Other guidelines introduce new requirements for full compliance with this specifcation or provide suggestions for implementers. All of these guidelines are designed to promote consistency among user agent implementations and to assist implementers in designing user agents that will be both usable and useful. By using consistent language to describe web site privacy practices, user agent implementers can help ensure that their implementations represent web site privacy practices accurately. In addition, consistent implementations serve to reduce the uncertainty web site operators have about how their policies will be displayed by P3P user agents.

6.1 Completeness of Human-Readable Translations

P3P user agents may display human-readable translations of P3P policies. Because of the large number of fields in a P3P policy, in some case, user agent implementers may wish to develop human-readable translations that do not include all P3P policy elements. The following guidelines are designed to reduce the chance that abridged translations may mislead users.

6.2 Plain Language Translations of P3P Vocabulary Elements

Section 3 includes normative definitions for all P3P vocabulary elements. However, many of these definitions are rather verbose and use language that is unsuitable for display to end users. Therefore, the P3P 1.1 Working Group has developed a set of "plain language" translations for most of the P3P vocabulary elements. These translations are designed to convey the essence of each element in relatively simple language, without conflicting with the normative definition. A "plain English" version is presented here, translations to other languages will be posted on the W3C Web-site when they become available. P3P user agents SHOULD display P3P policy information to users using the plain English wording shown here or an equivalent translation.

6.3 Storage of P3P Policies and Translations

P3P user agents SHOULD include mechanisms that allow users to store P3P policies and their corresponding translations easily to make them available for later viewing or printing.

6.4 Compact Policy Processing

P3P user agents MUST NOT rely on P3P compact policies that do not comply with the P3P 1.0 or P3P 1.1 specifications or are obviously erroneous. Such compact policies SHOULD be deemed invalid and the corresponding cookies should be treated as if they had no compact policies. The following guidelines are designed to reduce the chance that a P3P user agent will accept an invalid compact policy.

6.5 Sanity Checking P3P Policies

Although the P3P 1.1. specification does not hold user agents responsible for verifying that web site P3P policies are accurate, it is a good idea for user agents to do some sanity checking to flag P3P policies that are obviously erroneous. Such policies should be deemed invalid. The following guidelines are designed to reduce the chance that a P3P user agent will accept an invalid policy. (See also section 2.4.4 Policy and Policy Reference File Processing by User Agents.)

6.6 Timing of Notices to Users

P3P 1.0 element definitions and translations
P3P Element	Attribute	Plain Language Translation
POLICY	discuri (attribute of POLICY element)	Read our full privacy policy at [with link to discuri]
POLICY	opturi (attribute of POLICY element)	Find out how to opt-in or opt-out at [with link to opturi]
ENTITY	This policy is issued by: [display all entity information provided by site]
ACCESS	Your access to information about you:
ACCESS	nonident	We do not keep any information identified with you
ACCESS	all	We give you access to all of our information identified with you
ACCESS	contact-and-other	We give you access to your contact information and some of our other information identified with you
ACCESS	ident-contact	We give you access to only your contact information in our records
ACCESS	other-ident	We allow you to access some of our information identified with you, but not your contact information
ACCESS	none	We do not give you access to our information about you
DISPUTES	Ways to resolve privacy-related disputes with us include:
DISPUTES	service	[display long description and short description, if provided, with hyperlink to service URI, otherwise display "customer service" with hyperlink to service URI]
DISPUTES	independent	[display long description and short description, if provided, with hyperlink to service URI, otherwise display "independent organization" with hyperlink to service URI]
DISPUTES	court	We believe that the following authority offers recourse for disputes: [display long description and short description, if provided, with hyperlink to service URI, otherwise display "possible legal complaint" with hyperlink to service URI]
DISPUTES	law	We believe that the following laws or regulations provide recourse: [display long description and short description, if provided, with hyperlink to service URI, otherwise display "law" with hyperlink to service URI]
REMEDIES	[no heading - display this following corresponding disputes element]
DISPUTES	correct	We will correct any errors we make related to the commitments in our privacy policy
DISPUTES	money	We will compensate individuals if it is determined that we have violated our privacy policy
DISPUTES	law	Our privacy policy references a law that may determine remedies for breaches of our policy
NON-IDENTIFIABLE	We do not keep any information that could be used to identify you personally
PURPOSE	The ways your information may be used:
PURPOSE	current	To provide the service you requested
PURPOSE	admin	To perform web site and system administration
PURPOSE	develop	For research and development, but without connecting any information to you
PURPOSE	tailoring	To customize the site for your current visit only
PURPOSE	pseudo-analysis	To do research and analysis in which your information may be linked to an ID code but not to your personal identity
PURPOSE	pseudo-decision	To make decisions that directly affect you without identifying you, for example to display content or ads based on links you clicked on previously
PURPOSE	individual-analysis	To do research and analysis that uses information about you
PURPOSE	individual-decision	To make decisions that directly affect you using information about you, for example to recommend products or services based on your previous purchases
PURPOSE	contact	To contact you through means other than telephone (for example, email or postal mail) to market services or products
PURPOSE	historical	To aid in historical preservation as governed by a law or policy described in this privacy policy
PURPOSE	telemarketing	To contact you by telephone to market services or products
PURPOSE	other-purpose	For other uses: [include site's human, readable explanation; if site omits human-readable explanation say "not described here"]
PURPOSE	required (attribute of purpose and recipients elements)	(attribute, see below)
PURPOSE	required always	(no remark)
PURPOSE	required opt-in	[append to purpose/recipient] -- only if you request this
PURPOSE	required opt-out	[append to purpose/recipient] -- unless you opt-out
RECIPIENT	With whom we may share your information
RECIPIENT	ours	Companies that help us fulfill your requests (for example, shipping a product to you), but these companies must not use your information for any other purpose
RECIPIENT	delivery	Delivery companies that help us fulfill your requests and who may also use your information in other ways
RECIPIENT	same	Companies that have privacy policies similar to ours
RECIPIENT	other-recipient	Companies that are accountable to us, though their privacy policies may be different from ours
RECIPIENT	unrelated	Other companies whose privacy policies are unknown to us
RECIPIENT	public	People who may access your information from a public area, such as a bulletin board, chat room, or directory
RECIPIENT	required (attribute of purpose and recipients elements)	(attribute, see below)
RECIPIENT	required always	(no remark)
RECIPIENT	required opt-in	[append to purpose/recipient] -- only if you request this
RECIPIENT	required opt-out	[append to purpose/recipient] -- unless you opt-out
RETENTION	How long we may keep your information
RETENTION	no-retention	We do not keep your information beyond your current online session
RETENTION	stated-purpose	We keep your information only long enough to perform the activity for which we collected it
RETENTION	legal-requirement	We keep your information only as long as we need to for legal purposes
RETENTION	business-practices	Our full privacy policy explains how long we keep your information
RETENTION	indefinitely	We may keep your information indefinitely
CATEGORIES	We may collect the following types of information about you
CATEGORIES	physical	Name, address, phone number, or other physical contact information
CATEGORIES	online	Email address or other online contact information
CATEGORIES	uniqueid	Website login IDs and other identifiers (excluding government IDs and financial account numbers)
CATEGORIES	purchase	Information about your purchases, including payment methods
CATEGORIES	financial	Financial information such as accounts, balances, and transaction history
CATEGORIES	computer	Information about the computer you are using, such as its hardware, software, or Internet address
CATEGORIES	navigation	Which pages you visited on this web site and how long you stayed at each page
CATEGORIES	interactive	Activities you engaged in at this web site, such as your searches and transactions
CATEGORIES	demographic	Information about social and economic categories that might apply to you, such as your gender, age, income, or where you are from
CATEGORIES	content	Messages you send to us or post on this site, such as email, bulletin board postings, or chat room conversations
CATEGORIES	state	Cookies and mechanisms that perform similar functions
CATEGORIES	political	Which groups you might be a member of such as religious organizations, trade unions, and political parties
CATEGORIES	health	Health information such as information about your medical condition or your interest in health-related topics, services, or products
CATEGORIES	preference	Information about your tastes or interests
CATEGORIES	location	Information about an exact geographic location, such as data transmitted by your GPS-enabled device
CATEGORIES	government	Government-issued identifiers such as social security numbers
CATEGORIES	other-category	Other types of data: [include site's human, readable explanation; if site omits human-readable explanation say "not described here"]
CATEGORIES	optional (attribute of data elements)	if no: the data element is required [append to data element or category] if yes: the data element is optional [append to data element or category]

As a best practice, users should receive notice about a site's privacy practices prior to their user agent transmitting any personal data. Personal data means anything which might reasonably be linked to the user (see section 1.3.3 Identity Definitions) and as such can even include IP addresses and locale data transmitted in http headers before a page has even loaded. In order to present such notice, a user agent would need to fetch a P3P policy prior to loading a page following the guidelines specified in section 2.4.3 The Safe Zone. However, implementers will need to consider the performance, usability, and privacy tradeoffs associated with displaying privacy information prior to loading a page. One way that privacy and usability might be simultaneously maximized is to treat all requests made prior to display of policy information as safe zone requests.

At sites that include form fields, user agents SHOULD provide notice about the corresponding privacy practices prior to form submittal. Besides being best practice, this may be needed in order to comply with regulations in some jurisdictions (such as the European Union) that require a notice about the purpose of data collection to be presented to the user before any personal information is captured. User interface designs should recognize that the privacy policy for the form's action [URI] may be different than the privacy policy for the HTML page in which the form is embedded. In order to allow users to view privacy policy information associated with action URIs prior to form submittal, user agents might include a privacy tab that loads policy information for action URIs as a page loads, a button or menu item that causes policy information for action URIs to be displayed, or a pop-up that appears when a user begins entering information into a form field.

7. Appendices

Appendix 1: References (Normative)

Appendix 2: References (Non-Normative)

Appendix 3: The P3P 1.0 base data schema Definition (Normative)

The data schema corresponding to the P3P base data schema follows for easy reference. The schema is also present as a separate file at the URI http://www.w3.org/TR/P3P/base .

Appendix 4: XML Schema Definition of P3P 1.0 (Normative)

This appendix contains the XML schema for P3P policy reference files, for P3P policy documents, and for P3P data schema documents. P3P policy reference files, P3P policy documents and P3P data schema documents are XML documents that MUST conform to this schema. Note that this schema is based on the XML Schema specification [XML-Schema1][XML-Schema2]. The schema is also present as a separate file at the URI http://www.w3.org/2002/01/P3Pv1.xsd .

Appendix 5: The XML Schema for P3P 1.1 Extensions and the P3P generic attribute

Appendix 6: ABNF Notation (Normative)

The formal grammar of P3P is given in this specification using a slight modification of [ABNF]. The following is a simple description of the ABNF.

Appendix 7: P3P Guiding Principles (Non-normative)

The Platform for Privacy Preferences Project (P3P) has been designed to be flexible and support a diverse set of user preferences, public policies, service provider polices, and applications. This flexibility will provide opportunities for using P3P in a wide variety of innovative ways that its designers had not imagined. The P3P Guiding Principles were created in order to: express the intentions of the members of the P3P Working Groups when designing this technology and suggest how P3P can be used most effectively in order to maximize privacy and user confidence and trust on the Web. In keeping with our goal of flexibility, this document does not place requirements upon any party. Rather, it makes recommendations about 1) what should be done to be consistent with the intentions of the P3P designers and 2) how to maximize user confidence in P3P implementations and Web services. P3P was intended to help protect privacy on the Web. We encourage the organizations, individuals, policy-makers and companies who use P3P to embrace the guiding principles in order to reach this goal.

Information Privacy

P3P has been designed to promote privacy and trust on the Web by enabling service providers to disclose their information practices, and enabling individuals to make informed decisions about the collection and use of their personal information. P3P user agents work on behalf of individuals to reach agreements with service providers about the collection and use of personal information. Trust is built upon the mutual understanding that each party will respect the agreement reached.

Service providers should preserve trust and protect privacy by applying relevant laws and principles of data protection and privacy to their information practices. The following is a list of privacy principles and guidelines that helped inform the development of P3P and may be useful to those who use P3P:

In addition, service providers and P3P implementers should recognize and address the special concerns surrounding children's privacy.

Timing of Policy Evaluation and Notices to Users

Service providers should provide timely and effective notices of their information practices, and user agents should provide effective tools for users to access these notices and make decisions based on them.

Certain jurisdictions view the storage of cookies on a user's hard drive as an act of data processing. In such jurisdictions (e.g. the EU), policies should always be evaluated before a cookie is set and cookies should not be stored unless the cookie's policy is found to comply with the user's preferences.

Choice and Control

Users should be given the ability to make meaningful choices about the collection, use, and disclosure of personal information. Users should retain control over their personal information and decide the conditions under which they will share it.

Fairness and Integrity

Service providers should treat users and their personal information with fairness and integrity. This is essential for protecting privacy and promoting trust.

Security

While P3P itself does not include security mechanisms, it is intended to be used in conjunction with security tools. Users' personal information should always be protected with reasonable security safeguards in keeping with the sensitivity of the information.

Appendix 8: Working Group Contributors (Non-normative)

The P3P 1.1 Specification was produced by the P3P 1.1 Specification Working Group. The following individuals contributed: Lorrie Cranor (Chair), Diana Alonso-Blas (European Commission), Eric Brunner-Williams (Invited Expert), Brooks Dobbs (Doubleclick Inc), Bill Duserick (Fidelity), Jeff Edelen ( American Express), Serge Egelman (CMU), Jeremy Epling (Microsoft), Giles Hogben (JRC), Jack Humphrey (Invited Expert), Patrick C. K. Hung (CSIRO), Marc Langheinrich (ETH Zürich), Helena Lind (Ericsson), Matthias Schunter (IBM Zürich), Ari Schwartz (CDT), David Stampley (Invited Expert), Rigo Wenning (W3C)

The P3P 1.0 specification was produced by the P3P Specification Working Group. The following individuals participated in the P3P Specification Working Group, chaired by Lorrie Cranor (AT&T): Mark Ackerman (University of California, Irvine), Margareta Björksten (Nokia), Eric Brunner (Engage), Joe Coco (Microsoft), Brooks Dobbs (DoubleClick), Rajeev Dujari (Microsoft), Matthias Enzmann (GMD), Patrick Feng (RPI), Aaron Goldfeder (Microsoft), Dan Jaye (Engage), Marit Koehntopp (Privacy Commission of Land Schleswig-Holstein, Germany), Yuichi Koike (NEC/W3C), Yusuke Koizumi (ENC), Daniel LaLiberte (Crystaliz), Marc Langheinrich (NEC/ETH Zürich), Daniel Lim (PrivacyBank), Ran Lotenberg (IDcide), Massimo Marchiori (W3C/MIT/UNIVE), Christine McKenna (Phone.com, Inc.), Mark Nottingham (Akamai), Paul Perry (Microsoft), Jules Polonetsky (DoubleClick), Martin Presler-Marshall (IBM), Joel Reidenberg (Fordham Law School), Dave Remy (Geotrust), Ari Schwartz (CDT), Noboru Shimizu (ENC), Rob Smibert (Jotter Technologies Inc.), Tri Tran (AvenueA), Mark Uhrmacher (DoubleClick), Danny Weitzner (W3C), Michael Wallent (Microsoft), Rigo Wenning (W3C), Betty Whitaker (NCR), Allen Wyke (Engage), Kevin Yen (Netscape), Sam Yen (Citigroup), Alan Zausner (American Express).

The P3P Specification Working Group inherited a large part of the specification from previous P3P Working Groups. The Working Group would like to acknowledge the contributions of the members of these previous groups (affiliations shown are the members' affiliations at the time of their participation in each Working Group).

The P3P Implementation and Deployment Working Group, chaired by Rolf Nelson (W3C) and Marc Langheinrich (NEC/ETH Zurich): Mark Ackerman (University of California, Irvine), Rob Barrett (IBM), Joe Coco (Microsoft), Lorrie Cranor (AT&T), Massimo Marchiori (W3C/MIT), Gabe Montero (IBM), Stephen Morse (Netscape), Paul Perry (Microsoft), Ari Schwartz (CDT), Gabriel Speyer (Citibank), Betty Whitaker (NCR).

The P3P Syntax Working Group, chaired by Steve Lucas (Matchlogic): Lorrie Cranor (AT&T), Melissa Dunn (Microsoft), Daniel Jaye (Engage Technologies), Massimo Marchiori (W3C/MIT), Maclen Marvit (Narrowline), Max Metral (Firefly), Paul Perry (Firefly), Martin Presler-Marshall (IBM), Drummond Reed (Intermind), Joseph Reagle (W3C).

The P3P Vocabulary Harmonization Working Group, chaired by Joseph Reagle (W3C): Liz Blumenfeld (America Online), Ann Cavoukian (Information and Privacy Commission/Ontario), Scott Chalfant (Matchlogic), Lorrie Cranor (AT&T), Jim Crowe (Direct Marketing Association), Josef Dietl (W3C), David Duncan (Information and Privacy Commission/Ontario), Melissa Dunn (Microsoft), Patricica Faley (Direct Marketing Association), Marit Köhntopp (Privacy Commissioner of Schleswig-Holstein, Germany), Tony Lam (Hong Kong Privacy Commissioner's Office), Tara Lemmey (Narrowline), Jill Lesser (America Online), Steve Lucas (Matchlogic), Deirdre Mulligan (Center for Democracy and Technology), Nick Platten (Data Protection Consultant, formerly of DG XV, European Commission), Ari Schwartz (Center for Democracy and Technology), Jonathan Stark (TRUSTe).

The P3P Protocols and Data Transport Working Group, chaired by Yves Leroux (Digital): Lorrie Cranor (AT&T), Philip DesAutels (Matchlogic), Melissa Dunn (Microsoft), Peter Heymann (Intermind), Tatsuo Itabashi (Sony), Dan Jaye (Engage), Steve Lucas (Matchlogic), Jim Miller (W3C), Michael Myers (VeriSign), Paul Perry (FireFly), Martin Presler-Marshall (IBM), Joseph Reagle (W3C), Drummond Reed (Intermind), Craig Vodnik (Pencom Web Worlds).

The P3P Vocabulary Working Group, chaired by Lorrie Cranor (AT&T): Mark Ackerman (W3C), Philip DesAutels (W3C), Melissa Dunn (Microsoft), Joseph Reagle (W3C), Upendra Shardanand (Firefly).

The P3P Architecture Working Group, chaired by Martin Presler-Marshall (IBM): Mark Ackerman (W3C), Lorrie Cranor (AT&T), Philip DesAutels (W3C), Melissa Dunn (Microsoft), Joseph Reagle (W3C).

Finally, Appendix 7 is drawn from the W3C Note "P3P Guiding Principles", whose signatories are: Azer Bestavros (Bowne Internet Solutions), Ann Cavoukian (Information and Privacy Commission Ontario Canada), Lorrie Faith Cranor (AT&T Labs-Research), Josef Dietl (W3C), Daniel Jaye (Engage Technologies), Marit Köhntopp (Land Schleswig-Holstein), Tara Lemmey (Narrowline; TrustE), Steven Lucas (MatchLogic), Massimo Marchiori (W3C/MIT), Dave Marvit (Fujitsu Labs), Maclen Marvit (Narrowline Inc.), Yossi Matias (Tel Aviv University), James S. Miller (MIT), Deirdre Mulligan (Center for Democracy and Technology), Joseph Reagle (W3C), Drummond Reed (Intermind), Lawrence C. Stewart (Open Market, Inc.).

[1]	p3p-header	=	`P3P: ` p3p-header-field *(`,` p3p-header-field)
[2]	p3p-header-field	=	policy-ref-field \| compact-policy-field \| extension-field
[3]	policy-ref-field	=	`policyref="` URI-reference `"`
[4]	extension-field	=	token [`=` (token \| quoted-string) ]
Here, `URI-reference` is defined as per RFC 2396 [URI], `token` and `quoted-string` are defined by [HTTP1.1].

[5]	p3p-link-tag	=	`<link rel="P3Pv1" href="` URI `">`
Here, `URI` is defined as per RFC 2396 [URI].

[8]	expiry	=	"<EXPIRY" (absdate\|reldate) "/>"
[9]	absdate	=	`date="` HTTP-date `"`
[10]	reldate	=	`max-age="` delta-seconds `"`
Here, HTTP-date is defined in section 3.3.1 of [HTTP1.1], and delta-seconds is defined in section 3.3.2 of [HTTP1.1].

[11]	policy-ref	=	`<POLICY-REF about="` URI-reference `">` include exclude cookie-include cookie-exclude method-element extension `</POLICY-REF>`
Here, `URI-reference` is defined as per RFC 2396 [URI].

[12]	include	=	"<INCLUDE>" relativeURI "</INCLUDE>"
[13]	exclude	=	"<EXCLUDE>" relativeURI "</EXCLUDE>"
Here, `relativeURI` is defined as per RFC 2396 [URI], with the addition that the '`*`' character is to be treated as a wildcard, as defined in section 2.3.2.1.2.

[14]	hint	=	`<HINT scope="` scheme ( `://` \| `:/` ) authority `" path="` relativeURI `/>`
Here, `scheme`, `authority` and `relativeURI` are taken from RFC 2965 [STATE].

[17]	method-element	=	`<METHOD>` Method `</METHOD>`
Here, `Method` is defined in the section 5.1.1 of [HTTP1.1].

[18]	xml-lang	=	` xml:lang="` language `"`
Here, `language` is a language identifier as defined in [LANG].

[30]	disputes-group	=	"<DISPUTES-GROUP>" extension 1dispute *extension "</DISPUTES-GROUP>"
[31]	dispute	=	"<DISPUTES" " resolution-type=" '"'("service"\|"independent"\|"court"\|"law")'"' " service=" quoted-URI [" verification=" quotedstring] [" short-description=" quotedstring] ">" extension [longdescription] [image] [remedies] extension "</DISPUTES>"
[32]	longdescription	=	<LONG-DESCRIPTION> PCDATA </LONG-DESCRIPTION>
[33]	image	=	"<IMG src=" quoted-URI [" width=" `"` number `"`] [" height=" `"` number `"`] " alt=" quotedstring "/>"
[34]	quotedstring	=	`"` string `"`
Here, `string` is defined as a sequence of characters (with " and & escaped), and `PCDATA` is defined as in [XML].

[35]	remedies	=	"<REMEDIES>" extension 1remedy *extension "</REMEDIES>"
[36]	remedy	=	"<correct/>" \| "<money/>" \| "<law/>"

The Platform for Privacy Preferences 1.1 (P3P1.1) Specification

W3C Working Draft 4 January 2005

Abstract

Status of This Document

Table of Contents

1. Introduction

1.1 The P3P 1.1 Specification

1.1.1 Goals and Capabilities of P3P 1.1

1.1.2 Example of P3P in Use

1.1.3 P3P Policies

1.1.4 P3P User Agents

1.1.5 Implementing P3P 1.1 on Servers

1.1.6 Future Versions of P3P

1.1.7 Backwards Compatibility

1.2 About this Specification

1.3 Identity Definitions in the P3P Specification

1.3.1 Identified Data

1.3.2 Non-Identifiable Data

1.3.3 Identifiers

1.3.4. Linked and Linkable Data

1.4 Terminology

2. Referencing Policies

2.1 Overview and Purpose of Policy References

2.2 Locating Policy Reference Files

2.2.1 Well-Known Location

2.2.2 HTTP Headers

2.3.2.9 Domain Relationships

2.3.2.9.1 OUR-HOST Extension

2.3.2.9.2 Cookie Playback

2.3.2.9.3 Extension to P3P Compact Policy Header

2.3.3 Applying a Policy to a URI

2.3.4 Forms and Related Mechanisms

2.4 Additional Requirements

2.4.1 Non-ambiguity

2.4.2 Multiple Languages

2.4.3 The Safe Zone

2.4.4 Policy and Policy Reference File Processing by User Agents

2.4.5 Security of Policy Transport

2.4.6 Policy Updates

2.4.7 Absence of Policy Reference File

2.4.8 Asynchronous Evaluation

2.5. The P3P Generic Attribute for XML Applications

2.6 Example Scenarios

3.1.1 English language policies

3.1.2 XML encoding of policies

3.2.1 The POLICIES element

3.2.2 The POLICY element

3.2.3 STATEMENT-GROUP-DEF element (EXTENSION)

3.2.5 The ENTITY element

3.2.7 The DISPUTES element

3.3.1 The STATEMENT element

3.3.2 The STATEMENT-GROUP element (EXTENSION)

3.3.3 The CONSEQUENCE element

3.3.5 The PURPOSE element

3.3.5.1 The PPURPOSE element (EXTENSION)

3.3.6 The RECIPIENT element

3.3.6.1 The JURISDICTION element (EXTENSION)

3.3.7 The RETENTION element

3.3.8 The DATA-GROUP and DATA elements

3.4 Categories and the CATEGORIES element

4. Compact Policies

4.2.6 Compact RECIPIENT

4.2.7 Compact RETENTION

4.2.8 Compact CATEGORIES

4.2.9 Compact TEST

4.2.10 Compact STATEMENT

4.3 Compact Policy Scope

4.4 Compact Policy Lifetime

4.5 Transforming a P3P Policy to a Compact Policy

5. Data Schemas

5.1. Introduction

5.1.1. Backward Compatibility Requirements

5.1.2. P3P 1.1 Data Element Syntax Overview

5.2. How to express data types in P3P Policies

5.2.1 Basics

5.2.2 Categories in P3P Data Schemas

5.2.3 Variable-Category Data Elements

5.2.4 Referencing External Schemas

5.2.5 Natural Language description of data elements

5.3 Defining new Schemas

2.3.2.9.1 `OUR-HOST` Extension

3.2.1 The `POLICIES` element

3.2.2 The `POLICY` element

3.2.3 `STATEMENT-GROUP-DEF` element (EXTENSION)

3.2.5 The `ENTITY` element

3.2.7 The `DISPUTES` element

3.3.1 The `STATEMENT` element

3.3.2 The `STATEMENT-GROUP` element (EXTENSION)

3.3.3 The `CONSEQUENCE` element

3.3.5 The `PURPOSE` element

3.3.5.1 The `PPURPOSE` element (EXTENSION)

3.3.6 The `RECIPIENT` element

3.3.6.1 The `JURISDICTION` element (EXTENSION)

3.3.7 The `RETENTION` element

3.3.8 The `DATA-GROUP` and `DATA` elements

3.4 Categories and the `CATEGORIES` element

4.2.6 Compact `RECIPIENT`

4.2.7 Compact `RETENTION`

4.2.8 Compact `CATEGORIES`

4.2.9 Compact `TEST`

4.2.10 Compact `STATEMENT`