Extracted from Last Call version of the Mobile Web Best Practices.
[CONTEXT] Take all reasonable steps to find out about the device/browser (client) capabilities, adaptation and other transformation that takes place for any instance of an access to a resource.
[CAPABILITIES] Exploit device capabilities. Do not take a least common denominator approach.
[DEFICIENCIES] Take reasonable steps to work around deficient implementations.
[TESTING] Carry out testing on actual devices as well as emulators.
[URIS] Keep the URIs of site entry points short.
[NAVBAR] Provide minimal navigation at the top of the page.
[BALANCE] Design the service with a broadly balanced navigation tree where numbers of links on pages is balanced against depth of navigation.
[THEMATIC_CONSISTENCY] Ensure that links provide a thematically coherent experience when accessed from a device other than the one on which they were captured.
[NAVIGATION] Use navigation mechanisms in a consistent manner.
[ACCESS_KEYS] Assign access keys to links in navigational menus and frequently accessed functionality.
[LINK_TARGET_ID] Clearly identify the target of each link. Use clear, concise, descriptive link text to help users decide whether to follow a link. Identify the implications of following a link if the target is notably large and the user might not anticipate this from the context.
[LINK_TARGET_FORMAT] Note the target file's format unless you know the device supports it.
[IMAGE_MAPS] Do not use image maps unless you know the target client supports them and has sufficient screen area and an appropriate means of selection, such as a stylus or navigation keys. When using image maps under these circumstances, use client side image maps unless the regions required cannot be described with an available geometric shape.
[SERVER_SIDE_IMAGE_MAPS] Do not use a server side image map unless you know that the client provides a means of selection within the image map.
[POP_UPS] Do not cause pop-ups or other windows to appear and do not change the current window without informing the user.
[AUTO_REFRESH] Do not create periodically auto-refreshing pages, unless you have informed the user and provided a means of stopping it.
[REDIRECTION] Do not use markup to redirect pages automatically. Instead, configure the server to perform redirects by means of HTTP 3xx codes.
[SUITABLE] Ensure that content is suitable for use in a mobile context.
[CLARITY] Use clear and simple language.
[LIMITED] Limit content to what the user has requested.
[PAGE_SIZE_USABLE] Divide pages into usable but limited size portions.
[PAGE_SIZE_LIMIT] Ensure that the overall size of page is appropriate to bandwidth, the memory limitations of the device and other device and delivery channel characteristics if they can be determined.
[SCROLLING] Limit scrolling to one direction, unless secondary scrolling cannot be avoided.
[SCROLLING_LIMIT] Limit secondary scrolling to objects that require it, where it cannot be avoided.
[CENTRAL_MEANING] Ensure that material that is central to the meaning of the page precedes material that is not.
[GRAPHICS_FOR_SPACING] Do not use graphics for spacing.
[LARGE_GRAPHICS] Do not use images that cannot be rendered by the device. Avoid large or high resolution images except where critical information would otherwise be lost.
[USE_OF_COLOR] Ensure that information conveyed with color is also available without color.
[COLOR_CONTRAST] Ensure that foreground and background color combinations provide sufficient contrast.
[BACKGROUND_IMAGE_SUPPORT] Do not use background images unless you know the device supports them.
[BACKGROUND_IMAGE_READABILITY] When using background images make sure that content remains readable on the device.
[PAGE_TITLE] Provide a short but descriptive page title.
[NO_FRAMES] Do not use frames.
[STRUCTURE] Ensure that perceivable structures within the content can be programmatically determined.
[TABLES_SUPPORT] Do not use tables unless the client is known to support them. Do not use multi-layer tables.
[TABLES_LAYOUT] Do not use tables for layout.
[TABLES_ALTERNATIVES] Where possible, use an alternative to tabular presentation.
[NON-TEXT_ALTERNATIVES] Provide textual alternatives for non-text elements.
[OBJECTS_OR_SCRIPT] Do not embed objects or script in pages unless you know the device supports them.
[IMAGES_SPECIFY_SIZE] Always specify the size of images in markup.
[IMAGES_RESIZING] Resize images at the server.
[VALID_MARKUP] Create documents that validate to published formal grammars.
[MEASURES] Do not use pixel measures and do not use absolute units in markup language attribute values and style sheet property values.
[STYLE_SHEETS_USE] Use style sheets to control layout and presentation, unless the device is known not to support them.
[STYLE_SHEETS_SUPPORT] Organize documents so that they may be read without style sheets.
[STYLE_SHEETS_SIZE] Keep style sheets as small as possible.
[MINIMIZE] Use terse efficient markup.
[CONTENT_FORMAT_SUPPORT] Send content in a format that is known to be supported by the device.
[CONTENT_FORMAT_PREFERRED] Where possible send content in a client's preferred format.
[CHARACTER_ENCODING_SUPPORT] Ensure that content is encoded using a character encoding that is known to be supported by the target device.
[CHARACTER_ENCODING_USE] Indicate in the response the character encoding being used.
[ERROR_MESSAGES] Provide informative error messages, and a means of navigating away from an error message back to useful information.
[COOKIES] Do not use cookies unless you know the device supports them.
[CACHING] Attach caching information to the content.
[MINIMIZE_KEYSTROKES] Keep the number of keystrokes to a minimum.
[AVOID_FREE_TEXT] Avoid free text entry where possible.
[PROVIDE_DEFAULTS] Provide pre-selected default values where possible.
[DEFAULT_INPUT_MODE] Specify a default text entry mode, language and/or input format, if the target device is known to support it.
[TAB_ORDER] Create a logical tab order through links, form controls and objects.
[CONTROL_LABELLING] Label all controls appropriately. Explicitly associate labels with controls where the device supports this. Position labels relative to controls appropriately.