W3C mobileOK Checker

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Detailed report

1. Markup

   The quality of the markup sent to mobile browsers will impact the reliability and smoothness of the rendering of the page. Markup validity is the first step to delivering content that can be parsed and rendered reliably by browsers. The recommended markup format for mobile content is XHTML Basic 1.1. But beyond validity, various tags and attributes have a specific impact in the mobile world. For instance, CSS style sheets should be used to control the layout of the page instead of presentational tags (e.g. center, big, or font) and images sizes should be defined in the markup to avoid reflows.

   • [medium] There is no page title
     The page title is displayed by most mobile devices on top of the screen, and to identify bookmarks. Given the limited size of mobile screens, it is an essential piece of information for the user.

     Define a short but descriptive title.

     Triggered by the resource under test.

     Related best practice:
     [PAGE_TITLE] Provide a short but descriptive page title.
   • [low] The document does not validate against XHTML Basic 1.1 or MP 1.2.
     The document uses elements or structures that are not allowed in the XHTML Basic 1.1 specification, and thus are likely to be problematic for mobile browsers.

     Check the page with the W3C Markup Validator

     Triggered by http://www.w3.org/2009/Talks/01-mobileok-polytechnice/template1.html:

     Line 7, Column 8 — The content of element type "html" is incomplete, it must match "(head,body)".

     Related best practice:
     [VALID_MARKUP] Create documents that validate to published formal grammars.
   • [low] The document does not contain a DOCTYPE declaration
     The DOCTYPE declaration at the top of an HTML document helps browsers optimize the parsing and rendering of the page.

     See Don't forget to add a doctype.
     This failure message may be returned when the page under test contains a syntactically invalid DOCTYPE. Refer to the Document Type Definition production rules if you think you are in that case.

     Triggered by the resource under test.

     Related best practice:
     [VALID_MARKUP] Create documents that validate to published formal grammars.
   • More than 10% of the page characters are extraneous (whitespaces or comments)
     Given the limitations of mobile networks, sending extraneous whitespaces and comments make pages slower and more costly to load.

     Remove useless whitespaces and comments by adding a cleaning step in the publication process (e.g. through tidy).

     Triggered by the resource under test.

     Related best practice:
     [MINIMIZE] Use terse, efficient markup.

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1. At the HTTP level

   The source of the messages in this category is to be found in the HTTP headers that were sent along with the page. They are most likely due to the Web server configuration for static files, or the way the server-side scripts are written for dynamic content. Making sure that HTTP headers are correctly defined is essential in a mobile context with a usually low bandwidth and high latency.

   • There is an error in the "Last-Modified" header
     Properly handling conditional GET requests based on the Last-Modified header allows browsers to reduce the amount of data to download. When a resource has not been modified since the last retrieval, the server should send back a 304 Not Modified when a request comes with If-Modified-Since.

     See Mark Nottingham's tutorial on caching to learn how to configure a server or adapt a server-side script to handle conditional GET requests.

     Triggered by the resource under test.

     Related best practice:
     [CACHING] Provide caching information in HTTP responses.
   • There is an error in the "ETag" header
     Properly handling conditional GET requests based on the ETag header allows browsers to reduce the amount of data to download. When a resource has not been modified since the last retrieval, the server should send back a 304 Not Modified when a request comes with If-None-Match.

     See Mark Nottingham's tutorial on caching to learn how to configure a server or adapt a server-side script to handle conditional GET requests.

     Triggered by the resource under test.

     Related best practice:
     [CACHING] Provide caching information in HTTP responses.
   • The document is not served as "application/xhtml+xml"
     The recommended media type for serving XHTML is application/xhtml+xml. More browsers are likely to support that media type, and optimize the rendering for it. application/vnd.wap.xhtml+xml is widely used and supported in mobile networks as well but is unlikely to be supported by non-mobile browsers.

     See how to properly configure server mime types. If the page under test uses a non-XML version of HTML, you should first consider switching to XHTML. In any case, do not serve a non-XML version of HTML with an application/xhtml+xml media type.
     Beware: some browsers have no support for application/xhtml+xml (e.g. Internet Explorer) and prompt users to download pages served as such. You should not serve XHTML content to browsers that do not support it. Use Content Negotiation to match the browser's capabilities. See the XHTML Media Types - Second Edition W3C note for more information and in particular the Compatibility Guidelines to follow to have XHTML documents rendered on both XHTML-aware and HTML-only user agents.

     Triggered by the resource under test:

     served as text/html

     Related best practice:
     [CONTENT_FORMAT_SUPPORT] Send content in a format that is known to be supported by the device.

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