W3C mobileOK Scheme 1.0

W3C Working Group Note 25 August 2009

This version:
Latest version:
Previous version:
Jo Rabin, dotMobi (mTLD Mobile Top Level Domain Limited)
Phil Archer, Institute of Informatics & Telecommunications (IIT), NCSR "Demokritos" (and previously with FOSI)


The mobileOK scheme allows content providers to promote their content as being suitable for use on very basic mobile devices. This document provides an overview of the scheme and references the documentation that composes it.

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 Group Note of the W3C mobileOK Scheme. It follows a period of evolution during which the Working Group considered defining two levels of mobileOK conformance, each with its own set of tests. mobileOK is presented here as a simplified and unified scheme in which the relationship with the Best Practices document, the Basic Tests and the Checker is made explicit. The only change since last publication in June 2009 is the correction of the Media Type for POWDER in sections 2.2.2 and 2.2.3. A complete list of earlier changes is available. The Working Group does not expect further versions of this document.

Publication as a Working Group Note 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.

This document has been produced by the Mobile Web Best Practices Working Group as part of the Mobile Web Initiative. Please send comments on this document to the working group's public email list public-bpwg-comments@w3.org , a publicly archived mailing list.

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

Table of Contents

1. The mobileOK Scheme

mobileOK is designed to improve the Web experience for users of mobile devices by rewarding content providers that adhere to good practice when delivering content to them.

mobileOK says nothing about what may be delivered to non-mobile devices; furthermore, mobileOK does not imply endorsement or suitability of content. For example, it must not be assumed that mobileOK content is of higher informational value, is more reliable, more trustworthy, is or is not appropriate for children etc.

1.1 mobileOK Basic Tests 1.0

mobileOK Basic Tests 1.0 [mobileOK] specifies a number of tests that HTTP responses must pass when a URI is requested with a specific set of HTTP headers in the request. The tests are designed to be machine processable and to provide confidence that content will display well on very basic mobile devices.

1.2 Mobile Web Best Practices 1.0

mobileOK Basic Tests 1.0 is itself based on Mobile Web Best Practices 1.0 [BP], which provides a set of sixty guidelines for making content work well across a wide variety of mobile devices.

1.3 The Default Delivery Context

The HTTP Request headers used in mobileOK Basic Tests 1.0 identify a hypothetical user agent called the "Default Delivery Context" (DDC). The values of the key properties of the DDC (screen width, formats supported and other basic characteristics) are set at the minimum possible, while still supporting a Web experience.

The DDC is thus not a target to aspire to, it merely sets a base line below which content providers do not need to provide their content. It is Best Practice (see Best Practice [CAPABILITIES]) for content providers, as well as targetting DDC level devices, also to provide experiences for more advanced mobile devices that have capabilities not supported by the DDC.

1.4 mobileOK Checker

A software package called the mobileOK Checker [CHECK], has been developed by the Best Practices Working Group to provide automated checking of conformance. The package is in Java, and is open source. It is available under a W3C License.

W3C has created a Web interface as part of the W3C Validator, which uses this package. Other Web based checkers, by dotMobi (see ready.mobi) and CTIC (see TAWDIS) have also been created that adhere to the mobileOK Basic Tests 1.0 [mobileOK].

2 Claiming Conformance

Content Providers may wish to identify that their content is mobileOK conformant. This means that it can be requested so that the response conforms to mobileOK Basic Tests 1.0 [mobileOK] and hence will provide at least a functional user experience on mobile devices. A claim may only be made of a URI that when dereferenced in the manner described in [mobileOK] yields a response that passes all the tests contained in mobileOK Basic Tests 1.0. Such a claim says nothing about other experiences that may be provided at the same URI, when dereferenced in a different way (e.g. with different User-Agent and Accept HTTP headers).

2.1 The mobileOK Icon

W3C provides a mobileOK icon that represents a claim that the content on which the icon is found is mobileOK conformant as described above.

The icon is most appropriately used on desktop representations of a resource for which a mobileOK representation is also available. In such a situation it acts as a signal to a desktop user that the content or service they are using is also available on a mobile device. Display of the mobileOK icon is usually inappropriate on a mobile device since whether the content is usable on their device or not will be fully apparent without it.

When displaying a mobileOK icon, the image should be served from the same server as the resource, not from the W3C site. Note that the image is provided in PNG format which is a further reason why it is not suitable for use on mobileOK representations of pages, though it may be used on other representations.

The icon is issued under W3C copyright and may only be used in accordance with the W3C mobileOK license [LICENSE], the key feature being that it may only be used in representations of resources that, when dereferenced in accordance with the mobileOK Basic Tests 1.0, pass those tests.

2.2 Machine Readable Identification

To enhance discoverability of mobileOK content, providers may wish to identify their material as being mobileOK using POWDER (see Claiming mobileOK Conformance Using POWDER). Content should then be linked to a claim as described in 2.2.3 Linking Resources to Claims.

2.2.1 Claiming mobileOK Conformance Using POWDER

The Protocol for Web Description Resources [POWDER] provides a means through which a claim of mobileOK conformance may be made about many resources at once, such as all those available from a Web site. Importantly, POWDER also provides a means of identifying the person, organization or entity that made the claim. These two features make POWDER's Description Resources an ideal transport mechanism for mobileOK conformance claims (mobileOK was a key use case for POWDER).

In the following (fictitious) example, on 25th June 2008 (line 5), the organization described at http://www.example.com/company.rdf#me (line 4) claimed that all the resources available from example.com (lines 9-11) were mobileOK (line 13). This makes use of a one-class RDF vocabulary with namespace http://www.w3.org/2008/06/mobileOK# and class name Conformant.

1  <?xml version="1.0"?>

2  <powder xmlns="http://www.w3.org/2007/05/powder#">

3    <attribution>
4      <issuedby src="http://www.example.com/company.rdf#me" />
5      <issued>2008-06-25T00:00:00</issued>

6      <supportedby src="http://example.net/checker/" />
7    </attribution>

8    <dr>
9      <iriset>
10       <includehosts>example.com</includehosts>

11     </iriset>

12     <descriptorset>
13       <typeof src="http://www.w3.org/2008/06/mobileOK#Conformant" />
14       <displaytext>The example.com webiste conforms to mobileOK</displaytext>

15       <displayicon src="http://www.example.com/images/mobileOK.png" />
16     </descriptorset>
17   </dr>

18 </powder>

http://www.example.com/company.rdf#me (line 4) should lead to an RDF resource that describes the entity (either the foaf:Agent or dcterms:Agent) that provided the Description Resource. It is open to that organization to provide authentication methods to support its claim of mobileOK conformance. Note also in line 6 that POWDER's supportedby element has been used to refer to http://example.net/checker/, the implication being that the content of the described Web site has been tested using that checker. Lines 14 and 15 provide textual and graphical data that user agents may display to end users.

2.2.2 Linking Resources to Claims using the HTML link Element

All mobileOK resources are HTML. In the following example a powder document is linked using the link element (line 3). The value of the rel attribute, "describedby" is namespaced by the profile attribute of the head element (line 2) in versions of HTML that support it.

1  <html xmlns="http://www.w3.org/1999/xhtml">
2     <head profile="http://www.w3.org/2007/11/powder-profile">
3        <link rel="describedby" href="powder.xml" type="application/powder+xml"/>
4        <title>Welcome to example.com </title>
5     </head>
6     <body>
7        <p>Today's content is ....</p>
8     </body>
9  </html>

2.2.3 Linking Resources to Claims using the HTTP link Header

In many application environments it can also be appropriate to use HTTP Link [HTTP Link] headers. The following header is semantically equivalent to the HTML link header above.

Link: <powder.xml>; rel="describedby" type="application/powder+xml";

2.2.4 Other Forms of Claim

Other machine readable means of making a claim of mobileOK conformance are available. For example the following RDF triple asserts that the URI http://example.com is mobileOK conformant:

<http://example.com> rdf:type < http://www.w3.org/2008/06/mobileOK#conformant>

Other forms of expressing a claim may become available in the future.

3. Acknowledgements

The editors would like to thank members of the BPWG for contributions of various kinds.

Previous Editors:
Sean Owen, Google
Charles McCathieNevile, Opera Software

4. References

Mobile Web Best Practices 1.0, Jo Rabin, Charles McCathieNevile, W3C Recommendation 29 July 2008
W3C mobileOK Basic Tests 1.0, Sean Owen, Jo Rabin. W3C Recommendation 8 December 2008
W3C mobileOK Checker, BPWG Checker Task Force
W3C mobileOK License
Protocol for Web Description Resources (POWDER): Description Resources, Phil Archer, Kevin Smith, Andrea Perego, W3C Proposed Recommendation, 4 June 2009
Web Linking, Mark Nottingham, Internet Draft, 17 April 2009 (expires 19 October 2009, expected to advance to RFC status)