W3C mobileOK Scheme 1.0

Editor's Draft 17 October 2008

This version:
Latest Editor's version:
Previous version:
Jo Rabin, dotMobi
Phil Archer, Family Online Safety Institute


The mobileOK scheme allows content providers to promote their content as being suitable for use on 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 an Editor's Draft 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. It represents substantial change from previously published version.

The Working Group expects to publish this as a Note and not as a Recommendation track document.

Publication as a Editor's Draft does not imply endorsement by the Best Practices Working Group or by 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


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 mobile devices.

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 it not appropriate for children etc.

The mobileOK Claim

mobileOK provides a mechanism to represent, in a machine-processable way, a claim that content can be requested from URI so that the response conforms to mobileOK Basic 1.0 Tests [mobileOK] and hence will provide at least a functional user experience on mobile devices. Specifically, a claim of mobileOK 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. 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). A mobileOK claim may be made by the content provider themselves or any third party.

The mobileOK Trustmark

When making a mobileOK claim, content providers may add a visual indication, intended for humans, to communicate the presence of a claim. The trustmark is a W3C copyright image which may only be used in accordance with the W3C mobileOK license [LICENCE].

mobileOK Basic Tests

mobileOK Basic Tests [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 HTTP request. The tests are designed to be machine processable and to provide confidence that content will display well on basic mobile devices.

The Default Delivery Context

The HTTP Request headers used in mobileOK Basic Tests identify a hypothetical user agent called the "Default Delivery Context" (DDC). The values of the key properties of the DDC (screen with, 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 expected that content providers, as well as targetting DDC level devices will wish also to provide non-mobileOK experiences for more advanced devices.

Mobile Web Best Practices 1.0

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

mobileOK Checker

A software package known as the mobileOK Checker [CHECK], has been developed to provide automated checking of conformance. This package is used to provide a Web interface as part of the W3C Validator. The package is in Java, and is open source. It is available under the W3C License [@@link].

2. Claiming mobileOK Conformance

A claim of mobileOK conformance is made in a machine-readable way, by associating metadata with the resource that the claim relates to. A visual, i.e. human perceivable, trustmark may be used to indicate that a URI is capable of yielding mobileOK content may also be provided (See 3. Use of the mobileOK Trustmark).

Conformance claims may either be embedded in a resource (See RDFa) or may be made in a separate document formatted in RDF or POWDER.

Claims that are not embedded in a resource may be linked to from the resource as described in 2.4 Linking Resources to Claims.

2.1 mobileOK in RDF

To support claims of conformance with mobileOK, a one-class RDF vocabulary is defined. The namespace is http://www.w3.org/2008/06/mobileOK# and the class has the name Conformant. 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#>

2.2 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, the organization described at http://www.example.com/company.rdf#me claimed that all the resources available from example.com were mobileOK.

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://validator.w3.org/mobile/" />
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.w3.org/ICONS/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 the mobileOK Checker, the implication being that the content of the described Web site has been tested using the Checker. Lines 14 and 15 provide textual and graphical data that user agents may display to end users.

2.3 Claiming mobileOK Conformance using RDFa

RDF Annotation [RDFa] can be used to embed a claim of mobileOK conformance directly in an XHTML document as shown in the following example - however, note that RDFa should not be used in document instances that are themselves intended to be mobileOK as RDFa is not permitted in mobileOK documents.

1  <html 
2   xmlns="http://www.w3.org/1999/xhtml" version="XHTML+RDFa 1.0" 
3   xmlns:mok="http://www.w3.org/2008/06/mobileOK#" >
4   <head typeof="mok:Conformant">
5     <title>Document Title </title>
6    </head>

The version attribute on the html element is optional but is a clear signal to a processor that the document contains RDF annotations. The typeof attribute on the head is a shorthand way used in RDFa to assert the rdf:type relationship so that an RDFa-aware user agent will extract the RDF triple:

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

i.e. that the current document is an instance of the class of resources that conform to mobileOK.

Note that using RDFa to claim conformance with mobileOK implies that the entity making the claim is the content creator. Furthermore, user agents are given no clue as to how they may authenticate the claim. Therefore this method should not be seen as an equivalent method to using POWDER.

2.4 Linking Resources to Claims

All mobileOK resources are HTML. In the following example a powder document is linked using the link element. The value of the rel attribute, "powder" is namespaced by the profile attribute of the head element.

<html xmlns="http://www.w3.org/1999/xhtml">
   <head profile="http://www.w3.org/2007/11/powder-profile">
      <link rel="powder" href="powder.xml" type="application/xml"/>
      <title>Welcome to example.com </title>
      <p>Today's content is ....</p>


3. Using the MobileOK Trustmark

The W3C provides a logo or trustmark that can be used to indicate that a mobileOK version of the resource that carries it is available from the same URI that the resource that carries the trustmark was retrieved. Use of the trustmark is governed by the license agreement [@@@].

The trustmark 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 trustmark 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 trustmark, the image should be served from the same server as the resourece, but in any case not from the W3C site.

4. 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
Significant written contributions:
Dominique Hazaël-Massieux, W3C

5. 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 Working Draft 10 June 2008
W3C mobileOK Checker. Dominique Hazaël-Massieux, François Daoust
Protocol for Web Description Resources (POWDER): Description Resources. Phil Archer, Kevin Smith, Andrea Perego. W3C Working Draft 8 August 2008
RDFa in XHTML: Syntax and Processing Ben Adida, Mark Birbeck, Shane McCarron, Steven Pemberton. W3C Candidate Recommendation 20 June 2008