Compound Document by Reference Framework 1.0

W3C Working Draft 21 November 2005

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Timur Mehrvarz, Vodafone Group Services Limited
Daniel Appelquist, Vodafone Group Services Limited
Lasse Pajunen, Nokia


This document specifies the Compound Document Framework.

When combining separate markup languages, specific problems have to be resolved that are not addressed by their individual language specifications, such as the propagation of events across namespaces, the combination of rendering or the user interaction model.

Compound Document is the W3C term for a document that combines multiple formats.

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 the 21 November 2005 W3C Working Draft of the Compound Documents by Reference Framework. This is the first publication of the specification in this form. Previously this document formed part of the Compound Document Framework and WICD Profiles.

The Compound Document Formats Working Group explicitly requests comments on this specification. Please send them to public-cdf@w3.org, the public email list for issues related to compound documents on the Web. This list is archived and acceptance of this archiving policy is requested automatically upon first post. To subscribe to this list send an email to public-cdf-request@w3.org with the word subscribe in the subject line.

This document has been produced by the Compound Document Formats Working Group as part of the Rich Web Clients Activity within the W3C Interaction Domain.

This document was produced under the 5 February 2004 W3C Patent Policy. The Working Group maintains a public list of patent disclosures relevant to this document; that page also includes instructions for disclosing [and excluding] a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) with respect to this specification should disclose the information in accordance with section 6 of the W3C Patent Policy.

Per section 4 of the W3C Patent Policy, Working Group participants have 150 days from the title page date of this document to exclude essential claims from the W3C RF licensing requirements with respect to this document series. Exclusions are with respect to the exclusion reference document, defined by the W3C Patent Policy to be the latest version of a document in this series that is published no later than 90 days after the title page date of this document.

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.

Table of Contents

1 Compound Document Framework 1.0
    1.1 About this Document
    1.2 Scope
    1.3 Related Documents
    1.4 Reference and Inclusion
    1.5 Compound Document Schemas
        1.5.1 Schemas in case of reference
        1.5.2 Schemas in case of inclusion
    1.6 Identification and Versioning
        1.6.1 User Agent Identification
2 Compound Document by Reference (CDR) Framework 1.0
    2.1 Document Object Model
        2.1.1 Specialized DOM access
        2.1.2 Child to Parent DOM Access
        2.1.3 Parent to Child DOM Access
        2.1.4 SecurityException
        2.1.5 Single-threaded access to compound document DOM
    2.2 Events
        2.2.1 Event Propagation in a Compound Document
        2.2.2 Security Event
        2.2.3 Event-Related Legacy Markup
    2.3 Link Activation
        2.3.1 Child Documents
        2.3.2 Parent Documents
    2.4 Referencing child objects
        2.4.1 Referencing elements
        2.4.2 Declarative Child Object Parameters
    2.5 Security Considerations
        2.5.1 Phishing
        2.5.2 Firewall attack
        2.5.3 How this is handled today?


A Definitions
B Conformance
C References
D IDL Definitions
E Java Language Binding
F ECMAScript Language Binding
G Authoring Guidelines (Non-Normative)
H Acknowledgements (Non-Normative)
I Changes Log (Non-Normative)

1 Compound Document Framework 1.0

1.1 About this Document

(This section is informative)

All non normative sections are headed by: "(This section is informative)".

1.2 Scope

(This section is informative)

Combining content delivery formats can often be desirable in order to provide a seamless experience to the user.

For example, XHTML-formatted content can be augmented by SVG objects, to create a more dynamic, interactive and self adjusting presentation. A set of standard rules is required in order to provide this capability across a range of user agents and devices.

These are examples of compound documents:

  • XHTML + SVG + MathML
  • XHTML + XForms
  • XHTML + VoiceML

This document defines a generic Compound Document Framework that defines a language-independent processing model for combining arbitrary document formats.

NOTE: The Compound Document Framework is language-independent. While it is clearly meant to serve as the basis for integrating W3C's family of XML formats within its Interaction Domain (e.g., CSS, MathML, SMIL, SVG, VoiceXML, XForms, XHTML, XSL) with each other, it can also be used to integrate non-W3C formats with W3C formats or integrate non-W3C formats with other non-W3C formats.

1.3 Related Documents

(This section is informative)


WICD Core is the foundation of rich multimedia content and describes rules for combining Hypertext Markup Language (XHTML) and scalable child objects, such as Scalable Vector Graphics (SVG) in non device specific manner.

WICD Core builds upon CDF.

1.4 Reference and Inclusion

(This section is informative)

A namespace uniquely identifies a set of names so that there is no ambiguity when objects having different origins but the same names are mixed together. An XML namespace is a collection of element type and attribute names. These element types and attribute names are uniquely identified by the name of the unique XML namespace of which they are a part. In an XML document, any element type or attribute name can thus have a two-part name consisting of the namespace name and the element or attribute name.

A compound document by inclusion combines XML markup from several namespaces into a single physical document. A number of standards exist, and continue to be developed, that are descriptions of XML markup within a single namespace. XHTML, XForms, VoiceXML, and MathML are some of the prominent examples of such standards, each having its own namespace. Each of these specifications focuses on one aspect of rich-content development. For example, XForms focuses on data collection and submission, VoiceXML on speech, and MathML on the display of mathematical notations.

To authors of content, each of these many standards is useful and important. However, it is the combination of elements of any number of these standards that lends true flexibility and power to rich document creation. A document may exist to be displayed within a web browser, to display an input form, with a scalable graphic and a bit of mathematical notation, all on the same page. XHTML, XForms, SVG, and MathML, respectively, serve these needs, and could therefore be combined into a single multi-namespace document.

Consider this simple example, a compound document combining XHTML and MathML. The namespace declarations are marked by an appended comment to match the numbered namespaces listed below in the XML source in Example 1.

  1. XHTML Namespace declaration. The namespace for XHTML 1.0 is declared. Each XHTML element in the example below is qualified with the xhtml: namespace prefix.

  2. MathML Namespace declaration. The namespace for MathML 2.0 is declared. Each MathML element in the example below is qualified with the mathml: prefix.

A compound document example:

<?xml version="1.0" encoding="iso-8859-1"?>
<xhtml:html xmlns:xhtml="http://www.w3.org/1999/xhtml">   <!-- 1 -->
    <xhtml:h1>A Compound document</xhtml:h1>
    <xhtml:p>A simple formula using MathML in XHTML.</xhtml:p>
    <mathml:math xmlns:mathml="http://www.w3.org/1998/Math/MathML">   <!-- 2 -->

Example 1: A Simple Compound Document

A Compound Document

Figure 1: Rendered Simple Compound Document - This is a rendered version of the simple compound document in Example 1 which combines XHTML and MathML for rich content.

Compound documents may be composed of a single document that contains multiple namespaces, as seen in Example 1. This is a Compound Document “by Inclusion” (CDI). However, a compound document may also be composed over several documents in which one document of a particular namespace references another separate document of a different namespace.

For example, a root or top-most document might contain XHTML content for defining and formatting a page. This parent XHTML document can reference another document, , of another namespace, through the use of the XHTML <object> tag. This can be repeated for as many documents as needed. The root document plus this collection of separate, referenced documents is considered a Compound Document “by Reference” (CDR). See Figure 2 for a simple CDR document in which an XHTML root document contains a reference to a separate SVG child document having markup for three colored circles.

An XHTML document referencing an SVG document with 3 overlapping colored circles

Figure 2 (above): Compound Document by Reference - A simple compound document by reference where a XHTML document references a separate SVG document. Below you see the two markup fragments.


<?xml version="1.0"?>
<html xmlns="http://www.w3.org/1999/xhtml">
    <object height="350" width="600" type="image/svg+xml" data="circles.svg"/>


<?xml version="1.0" encoding="UTF-8"?>
<svg xmlns="http://www.w3.org/2000/svg">
  <g fill-opacity="0.7" stroke="black" stroke-width="0.2cm">
    <circle fill="red" cx="6cm" cy="2cm" transform="translate(0,50)" r="100"/>
    <circle fill="blue" cx="6cm" cy="2cm" transform="translate(70,150)" r="100"/>
    <circle fill="green" cx="6cm" cy="2cm" transform="translate(-70,150)" r="100"/>

And of course, a compound document may be a hybrid of both compound document by inclusion and compound document by reference.

1.5 Compound Document Schemas

Within a compound document, there are many schemas. Each combined language has its own schema and the compound document itself may have an additional schema. The schema handling differs between cases of compound by reference and by inclusion.

1.5.1 Schemas in case of reference

In compound by reference, each document has its own schema based on its language. For example, referencing XHTML document has its own schema and referenced SVG has its own.

Each document is handled separately and schemas are validated based on language on each document separately. Therefore, in case of compound by reference, there are no additions to current schema handling.

1.5.2 Schemas in case of inclusion

In compound by inclusion, the compound document has a merged schema. Because multiple languages are used within the same document, there is a need for merged schema to allow document validation.

However, the Compound Document Framework 1.0 does not specify how schemas are combined in cases based on inclusion. This is left for future version of the Compound Document Framework.

1.6 Identification and Versioning

Editorial note 
The group currently has no consensus on this proposal. Disadvantages of this solution are that it is not author friendly. Most people do not know about HTTP and know even less about sniffing HTTP headers. XHTML already has content negotiation by design. If a particular format referenced by an element is not supported the fallback content is rendered.

(This section is informative)

A distinct identification of the supported Compound Document capabilities is often not possible by the advertisement of a list of supported content types. Such a list is not able to sufficiently describe the supported capabilities between different media types. The name of a profile is often better suited to describe such characteristics.

It is therefor essential for CDF compliant agents to advertise a list of the profiles they support.

1.6.1 User Agent Identification

Editorial note 
The following is still under discussion. Alternatively, a user agent could advertise supported profiles by attaching the "profile=..." parameter to the content type string of the root document format, sent with the HTTP "accept:" header. Unfortunately, most user agents just advertise a small list of the content types they support. A growing number of user agents does only advertise "*/*".

For Compound Document profiles that define a unique profile name, compliant CDF user agents must advertise all supported profiles, using the "UA-Profiles:" header.


UA-Profiles: wicd, foocd

Any Compound Document profile specification is responsible for defining it's unique profile name, if it is required for that profile name to be advertised by the user agent.

A version number can be attached to a profile name. If no version number is provided, the agent can be expected to support version "1.0" of the named profile.


UA-Profiles: wicd:ver=1.1, foocd

An different version number refers, in general, to a complete new specification of the named profile. Whether a higher version number indicates a superset profile of a lower version number depends on the profile. If the profile specification document specifies this, then it is suggested for content providers, evaluating the version number, to accept a higher version number as a compliant implementation.

If no version number is provided, the agent can be expected to support version "1.0" of the named profile.

2 Compound Document by Reference (CDR) Framework 1.0

2.1 Document Object Model

Compound document profiles which leverage the Compound Document Framework and which support scripting must have scripting interfaces that are compatible with the DOM Level 3 Core Specification.

Compound document profiles may subset DOM Level 3 Core, but any DOM Core subsetting should be coordinated with other related DOM subsetting standards efforts. For example, mobile subset efforts for W3C languages such as XHTML, SVG, SMIL and XForms should be coordinated with each other because of the high likelihood that compound document profiles will be defined which combine these languages together.

A compound document using references consists of a number of child documents. Each child document contains elements and attributes from one or more namespaces. The corollary of this is that each child document generates its own DOM. The interaction points between parent and child documents of a compound document are at referencing DOM nodes in a parent document. The compound document framework provides means to access child and parent documents' DOM.

For the purposes of scripting and CSS cascading, these apply to the individual DOMs corresponding to each document in isolation. However, for events, CDR defines an event flow, where event can propagate from child to parent document.

2.1.1 Specialized DOM access

Many languages define specialized DOM APIs. The W3C has defined an HTML DOM which extends the Core DOM and provides various convenience APIs for interacting with HTML documents. Similarly, the SVG language defines an SVG DOM which extends Core DOM.

Compound document profiles must specify whether the specialized DOM APIs that are defined within the component languages are supported.

Note: Although not required for compliance with the Compound Document Framework, it is strongly recommended that compound document profiles support all specialized DOM APIs that are supported in the component languages.

2.1.2 Child to Parent DOM Access

User agent must provide access to parent document.

For a child document to access the parent document, this specification introduces the ReferencedDocument interface.

The ReferencedDocument interface only applies to objects implementing the Document interface defined in DOM Level 3 Core. [DOM3Core] profiles build upon this specification must specify on which exact document objects the interface must be implemented. User agents may implement this interface for each document object they consider to be viable.

IDL Definition:

interface ReferencedDocument {
  readonly attribute Element referencingElement;

The referencingElement attribute must represent the element node used for including the current document in the parent document. If access to the parent document is disabled or there is no parent document the attribute must be null.

2.1.3 Parent to Child DOM Access

User agents must provide access to child documents.

DOM Level 2 HTML defined a way for several elements to access the child document using the contentDocument attribute. [DOM2HTML] This specification defines a generic ReferencingElement interface.

The ReferencingElement only applies to objects implementing the Element interface defined in DOM Level 3 Core. [DOM3Core] Profiles build upon this specification must specify on which exact element objects the interface must be implemented. User agents may implement this interface for each element object they consider to be viable.

IDL Definition:

interface ReferencingElement {
  readonly attribute Document contentDocument;

The contentDocument attribute must represent the child document. If access to the child document is disabled or there is no child document the attribute must be null.

2.1.4 SecurityException

Accessing parent or child documents through the DOM as described in sections 2.1.2 and 2.1.3 can be disabled for security reasons. In such cases user agents should throw a SecurityException.

IDL Definition:

exception SecurityException {
  unsigned short   code;
// SecurityExceptionCode
const unsigned short      SECURITY_ERR       = 83;

code represents an integer indicating the type of error generated. SECURITY_ERR is given back if an attempt was made to break through the security policy of the user agent.

Editorial note 
Todo: Make sure 82 really is the latest used exception.

2.1.5 Single-threaded access to compound document DOM

The framework assumes a single-threaded execution model for accessing the compound document's object model via the DOM. As a result, during the time when one script or event handler executes against the DOM, no other script or event handler can access the DOM.

NOTE: This does not preclude multiple execution threads, such as asynchronous downloading of image files or custom logic that operates on other (non-DOM) data structures. It simply precludes multiple scripts or handlers from operating on the DOM at the same time.

2.2 Events

Compound document profiles which leverage the Compound Document Framework and which support events and interactivity must have event interfaces and an event processing model that are compatible with the DOM Level 3 Events Specification.

Compound document profiles may subset DOM Level 3 Events, but any DOM Events subsetting should be coordinated with other related DOM subsetting standards efforts. For example, mobile subset efforts for W3C languages such as XHTML, SVG, SMIL and XForms should be coordinated with each other because of the high likelihood that compound document profiles will be defined which combine these languages together.

2.2.1 Event Propagation in a Compound Document

Events propagate from a child component up to it's parent.

There are four different cases how event flow through references can happen.

  1. Object with external content <object src="file" />
  2. Object with inlined content <object><content /></object>
  3. Referenced image content <img src="file" /> (special case of 1)
  4. Directly inlined content <content /> (special case of 2)

Compound Document Framework 1.0 provides a way to disable event propagation from one document to the another.

Each case should behave in a same way. There should not be any behavioural differences on how the content is referenced. However, there might be differences in default value if event propagation is enabled or disabled by default.

Event propagation is controlled by a DOM attribute named: 'events'

'events' attribute may have values 'block' or 'propagate'. The default value depends on referencing element.

'events' attribute applies to all referencing elements. Each referencing element must specify which is the default value.

In XHTML, the 'object' element is used to reference child document content whilst in SVG the 'foreignObject' element is used to reference child content. The default behaviour in existing user agents is to isolate events between a parent document and a referenced child document. The default value of the 'events' attribute is 'block'.

This attribute is used to control event propagation across referencing elements in a compound document.

Setting the 'events' attribute to 'block' causes a CDF compliant user agent to block event propagation at the parent/child boundary.

Setting the 'events' attribute to 'propagate' allows events in the compound document to cross the referencing boundary such that event capture and bubbling occurs between the parent and child document.

2.2.2 Security Event

Security event is a mechanism for notifying non-scripting related security violations.

Every time a document tries to break through security user agents should dispatch a security event in the http://www.w3.org/2005/10/cdf namespace on the document object. The event is not cancelable and has no bubbling phase. It implements the Event interface defined in DOM Level 3 Events. [DOM3Events]. Note, this is not the final namespace for this event.

For example, when an event is bubbling to other document that might violate security policy, user agent must prevent bubbling and dispatch a security event. User agents are responsible for making a security policy that identifies cases when event is dispatched.

2.2.3 Event-Related Legacy Markup

In order to claim conformance to this Compound Documents Framework, a compound document profile must define how all of its event-related language constructs and scripting constructs map to corresponding DOM3 event facilities, unless DOM3 events has already defined the mapping. In particular:

  • For each event construct within supported languages, the profile must define the event's namespace and local name, what phases it supports (capture, target, bubble), whether it is cancellable, and the name of the DOM interface for its event structure (e.g., events.dom.w3c.org::UIEvent).

  • Any events that are defined to be equivalent to a corresponding event from DOM3 Events must have compatible behavior, such as the phases supported, cancellability and propagation across parent/child compound document boundaries. For example, for a "click" event from language A to be equivalent to the DOM3 "click" event, it also must be cancellable since DOM3 "click" is cancellable.

  • The profile must define how to map language features for event listeners, event handlers, and event targets into corresponding DOM3 Events facilities.

2.3 Link Activation

Link activation behavior for hyperlinks within a child object is defined by the child object's relevant language specification. For example, if the parent document is XHTML and the child object is SVG, then the SVG specification defines the behavior for what happens when a hyperlink within the SVG object is activated.

  • Link activation behavior for hyperlinks within a parent object is defined by the parent object's relevant language specification

  • Link activation behavior for hyperlinks within a child object is defined by the child object's relevant language specification

Nested hyperlinks are more complicated. The following illustrates nested hyperlinks. Suppose the parent document is XHTML as follows:

<!-- parent.html -->
<html:a href="LargeMap.html">
  <html:object type="image/svg+xml" data="child.svg"/>

And the child SVG document contains the following:

<!-- child.svg -->
<svg:a xlink:href="DetailedCountyMap.html">
  <svg:text>county map</svg:text>

The <svg:text> element is surrounded by two hyperlinks: a near one defined within the same SVG file and a farther one defined within the parent XHTML file. Nested hyperlinks for Compound Documents are processed in a manner consistent with the following model:

  • hyperlink-related event processing is compatible with the DOM3 Event model. Thus, an event such as a mouse click or a keyboard action which maps to DOMActivate will participate in capture, target and bubble phases according to the DOM3 Event specification.

  • elements which define hyperlinks (e.g., the <html:a> and <svg:a> elements) define implicit DOMActivate event listeners for the target and bubble phases (i.e., the useCapture parameter on the implicit addEventListenerNS() call is false), with a default action to execute a hyperlink to the identified resource.

  • the target element for pointer device events is established by first determining the most deeply nested child document which has content that intersects with the geometric (x,y) location of the event. Within the child document, the target element is chosen following the rules defined within the child document's language specification. (For example, the SVG specification says that the target element for pointer events generally is the topmost element on the canvas.)

The implication is that the behavior of nested hyperlinks depends on how the hyperlink is activated. Here are some examples which illustrate common possibilities:

  • Suppose the user gives focus to an <html:a> within the parent XHTML document above and then hits the "Enter" key to activate that link. In the example above, the <html:a> element is the event target. This would cause execution of the hyperlink to "LargeMap.html".

  • Suppose the user gives focus to an <svg:a> within the child SVG document and then hits the "Enter" key to activate that link. In the example above, the <svg:a> element is the event target. This would cause execution of the hyperlink to "DetailedCountyMap.html".

  • Suppose the user uses a mouse or other pointer device to click on the work "county map" in the above example. Because this pointing device event occurs over geometry controlled by both the parent XHTML and child SVG documents, and because the SVG document is the most deeply nested, then the target element will be chosen according to the rules in the SVG specification. In the example above, this will cause the <svg:text> element to be the event target. The <svg:a> element will receive the event after bubbling from the <svg:text> element, which will cause a hyperlink to "DetailedCountyMap.html".

2.3.1 Child Documents

(This section is informative)

Since the child document's language specification defines hyperlinking behavior, here are recommendations for language specifications for languages which might be used as child documents within the context of compound documents:

If specifications provide a mechanism for hyperlinking they MUST also define a way to target specific frames. In addition it MUST be defined how the current document can be replaced (the document the link is defined in), the parent document and the root document.

Relevant language specifications should include a mechanism for defining the possible targets for the hyperlink. For example, the HTML4 specification includes a 'target' attribute on the 'html:a' element which supports targets of _blank, _self, _parent, _top and <frametarget> (see http://www.w3.org/TR/html401/types.html#type-frame-target). The SVG Tiny 1.2 specification also supports a 'target' attribute on the 'svg:a' element with the same list of possible values, except with the addition of an "_replace" keyword (see http://www.w3.org/TR/SVGMobile12/linking.html#AElementTargetAttribute). The WebCGM specification also supports targets of _blank, _self, _parent, _top, _replace and <frametarget> (see http://www.w3.org/TR/REC-WebCGM/REC-03-CGM-IC.html#webcgm_3_1_2_2).

NOTE: The keyword _self means different things in SVG than it does in HTML. In HTML it replaces the current document and in SVG it replaces the parent document.

Relevant language specification should provide a clear definition of the behavior of the "_self" keyword. For SVG and WebCGM, when there is a parent HTML document which references an SVG or WebCGM graphic via html:object, the "_self" keyword causes the HTML document to be replaced by the linked content. However, when a parent HTML document references a child HTML document via html:object or html:iframe, some HTML browsers implement the "_self" keyword such that only the child HTML document is replaced. Because of this, relevant language specifications should be clear about UA behavior in response to the "_self" keyword. One strategy to consider: if the primary usage scenario falls under the category of "replaced element" (see http://www.w3.org/TR/REC-CSS2/conform.html#replaced-element), as is the case with SVG, then defining "_self" to replace the parent document is appropriate.

For language specifications such as SVG which define "_self" to replace the parent document, it might be appropriate to support a "_replace" feature similar to what exists in SVG Tiny 1.2 and WebCGM. This feature causes a hyperlink to replace the child document only but leave parents and other ancestor documents unchanged. (For example, if an SVG document is referenced by a parent HTML document via an 'html:object' element, and if the SVG document has an 'svg:a' element with target="_replace", then when that hyperlink is activated, the SVG document gets replaced but there are no changes within the parent HTML document.)

Sometimes in industry practice a plugin user agent is used to handle certain types of child documents. For example, plugins might handle SVG or MathML child documents. In these scenarios the plugin may only be able to handle particular formats via the "_replace" keyword. (For example, a MathML plugin might be able to handle only MathML content.) Because of this, relevant language specification that support "_replace" (or alternative syntax for the same feature) should clearly specify requirements when "_replace" references content of the same type and content of other types. (For example, only content of the same type can be referenced with "_replace", or any type can be referenced with "_replace", but then error processing must be defined for unknown or unsupported content.)

2.3.2 Parent Documents

(This section is informative)

One potential area of ambiguity in the context of compound document is the meaning of the "_self" and "_parent" keywords. (See HTML4's definition at http://www.w3.org/TR/html401/types.html#type-frame-target and SVG Tiny 1.2's definition at http://www.w3.org/TR/SVGMobile12/linking.html#AElementTargetAttribute). For example, suppose a parent XHTML document references a child SVG document via an 'html:object' element and suppose the SVG document has an 'svg:a' element with target="_self". The SVG Tiny 1.2 specification says that "_self" causes both the XHTML parent frame and the child SVG to be replaced when the hyperlink is activated.

However, there are potential ambiguities if the parent language format supports its own particular notions of nested regions (e.g., frames, panes or sub-documents). It is strongly recommended that relevant language specifications clearly define how its own nested region features relate to the hyperlinking keywords _self, _parent, and _top.

2.4 Referencing child objects

(This section is informative)

Each hosting language has its own methods to reference child objects. They provide different functionalities but following section describes common functionalities.

2.4.1 Referencing elements

(This section is informative)

In Compound Document Framework 1.0, embedding media and other objects is done by using the existing elements in the host languages rather than by extending them with new markup. In XHTML documents, the <object> element will be used to reference XML document types. In SVG documents, the <foreignObject> element is used. In SMIL, the ref element should be used.

2.4.2 Declarative Child Object Parameters

(This section is informative)

It may be necessary to transfer parameters declaratively to a referenced child object. Compound Document profiles may define specific parameters/values for this purpose. Two examples:

<object type="..." data="...">
  <param name="param1" value="true" />
  <param name="param2" value="123" />

<svg xmlns="http://www.w3.org/2000/svg">

2.5 Security Considerations

(This section is informative)

There may be security considerations to consider in allowing interaction between a document from one source and another from a different source. These will be investigated and described in this section.

2.5.1 Phishing

(This section is informative)

A common security problem on the Web is known as "phishing". A web application that looks like one which is trusted by the user collects some data (for example credit card numbers, addresses, etc), and then posts that information to a potentially hostile third party.

Allowing access across document boundaries potentially allows an object to fetch the actual document which is trusted by the user, and read the user's data as it is entered. This approach could defeat many browser interface features which are designed to warn the user that a site is not the one they think.

2.5.2 Firewall attack

(This section is informative)

Another common attack is to post a document to a user behind a firewall, and then use it to gain access to a server whose name is known but which is normally behind the firewall, and then post information from the retrieved resources to a hostile party.

2.5.3 How this is handled today?

(This section is informative)

Currently, the common approach used is to restrict access across documents or network interfaces to material which comes from the same source as the code which tries to make that access. This makes it difficult to re-use resources on the Web, by requiring a copy to be held in the domain of each application which uses that resource. This breaks cacheability, potentially reduces maintainability, and requires services to maintain the entire service rather than taking full advantage of specialised third-party providers.

There are several possible approaches to a security model which is less restrictive. Cross Document Messaging [1] is one such.

A Definitions

The working group has decided to use following terms in the work and this document.

Compound document

The compound document is a document that combines separate component languages either by reference or by inclusion.

Parent document

In the case of combining by reference, one compound document may be a collection of several separate documents.

A parent document must represent a document that has a DOM as defined by DOM Level 3 Core and reference another document. The DOM that is formed must be tree-based.

Root document

In the case of combining by reference, one compound document may be a collection of several separate documents.

The outermost parent document is called the root document.

Child document

In the case of combining by reference, one compound document may be a collection of several separate documents.

The document that is referenced is called Child document. If the Child document references other documents, it is also called Parent document.

Component Language

Component language refers to an XML-based language (like XHTML and SVG) with its own elements and attributes.


A document which logically includes other documents via a hypertext reference.

For example: XML 1.1 or HTML documents tied through hypertext reference producing as many DOM linked to one another.


A document which includes other documents by-value.

For example: A single XML 1.1 document making use of XML grammars defined independently, normally making use of multiple namespaces.

User Agent

See definition in Device Independence Glossary document.

B Conformance

This specification defines conformance for several classes of products:

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 (see ). However, for readability, these words do not appear in all uppercase letters in this specification.

At times, this specification recommends good practice for authors and user agents. These recommendations are not normative and conformance with this specification does not depend on their realization. These recommendations contain the expression "We recommend ...", "This specification recommends ...", or some similar wording.

Document Conformance

  1. All Compound Documents must have a root document which has a DOM.

  2. Conformant content SHOULD not raise security exceptions or events.

User Agent Conformance

  1. Conformant user agent MUST implement DOM interfaces.

C References


European Computer Manufacturers Association, "ECMAScript Language Specification 3rd Edition", December 1999, http://www.ecma-international.org/publications/standards/Ecma-262.htm

Also available as ISO/IEC 16262: 199


IETF, "Scripting Media Types", 06 June 2005 http://www.ietf.org/internet-drafts/draft-hoehrmann-script-types-03.txt


Document Object Model (DOM) Level 2 HTML Specification

latest version: http://www.w3.org/TR/2003/REC-DOM-Level-2-HTML-20030109/


Document Object Model (DOM) Level 3 Core Specification

latest version: http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/


OMG IDL Syntax and Semantics" defined in The Common Object Request Broker: Architecture and Specification, version 2, Object Management Group. The latest version of CORBA version 2.0 is available at http://www.omg.org/technology/documents/formal/corba_2.htm



D IDL Definitions

This appendix contains the complete OMG IDL [OMGIDL] for the Compound Document Framework 1.0 definitions.


#ifndef _CDF_IDL_
#define _CDF_IDL_

#pragma prefix "w3c.org"
module cdf
	interface ReferencedDocument {
		readonly attribute Element 	referencingElement;

	interface ReferencingElement {
  		readonly attribute Document 	contentDocument;

#endif // _CDF_IDL_

E Java Language Binding

This appendix contains the complete Java Language [Java] binding for the Compound Document Framework 1.0.


package org.w3c.cdf;

public interface ReferencedDocument {
	public Element getReferencingElement();


package org.w3c.cdf;

public interface ReferencingElement {
	public Document getContentDocument();

F ECMAScript Language Binding

This appendix contains the complete ECMAScript [ECMA] binding for the Compount Document Framework 1.0 definitions.

Object ReferencedDocument 
	The ReferencedDocument object has the following property:
			This read-only property is of type Element.
Object ReferencingElement 
	The ReferencingElement object has the following property:
			This read-only property is of type Document.

G Authoring Guidelines (Non-Normative)

Compound Document Framework 1.0 provides means for using multiple documents and combining presentation from parts. Authors are encouraged to use this method to enable reuse of the content.

Dividing content to reusable parts allow efficiency in content transfers. User agents may cache often used content that improves user experience and reduces need for transfering same content many times.

H Acknowledgements (Non-Normative)

The editors would like to thank the contributors:

I Changes Log (Non-Normative)

  • Changed the document title
  • Inserted section 1.6 Identification.
  • Inserted Java Language Binding (IDL).
  • Removed section 1.6 Identification.
  • Removed Java Language Binding (IDL).
  • Moved focus managent text to WICD
  • Applied Alex's update for Focus Management.
  • Updated the Abstract.
  • Split "CDF + WICD Core" document into "CDF" and "WICD Core"
  • Split main document into "CDF + WICD Core", "WICD Mobile" and "WICD Full"