Bandwidth efficiencies, Navigation aids

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Bandwidth efficiencies

Analysis of the target-user community should include evaluation of the expected (and worst case) bandwidth. Well-engineered Web pages data elements shall be responsive to the business, information, or service objectives of the page. Tools for well-engineered Web page generation should not add extraneous information such as the name/version of the tool used. It may be useful to have a well-engineered Web page size limit for a site, with warnings associated with links that lead to documents larger than the suggested size. Links to large items (e.g., pages, downloads, images, etc) should have size information as an RMfield (, <… class=”objectsize”>) associated with the link. Indicate the size of the object using true decimal size (not binary) in octets (eight bit elements) and either thousands (“k”), millions (“M”), or Gigaoctets (“G”). A 5 Gigaoctet image could be designated as: 5G, 5000M or 5000000k.

It is especially desirable to have the initial point of contact (home page) for a site load quickly so users can identify the content of the site. This is especially true when some users have low bandwidth connectivity. For this reason, the home page should contain few and small graphic files, and all graphics should contain height/width tags and alt tags so that a user can see quickly what the content of the page will be. Reusing images will have a positive impact on the overall performance.

Navigation aids

A link shall be provided in each well-engineered Web page to get to one or more appropriate pages for more general information relevant to this site (see 5.11). The information pages should provide a context for users who may have entered from links or search results into the middle of the site. These pages may include information about the page owner. This should include a link to the site’s home page and might also include owner organization, corporate department, physical location, etc. The location and appearance of navigation aids on the various pages of an Intranet should be consistent. For example, the navigation aid to move the user to the site home page should always be located in the same page position as defined by the high level design of the Web site. This also applies to the relative location and appearance of other navigation elements such as “Top of Page,” “last 25 items” or “next 25 items.” Each page should provide information such as mailto link for author or other point of contact for users. NOTE—Typically, this will not be “Webmaster@domain” as discussed in 5.7. Summaries and tables of contents of large documents should be available to allow for a quicker discard of uninteresting data/pages. The use of the id attribute with HTML elements is encouraged to facilitate future links31 to specific elements of a document. This can be particularly useful when a series of pages have common structural elements. For example, standards have a “scope” section, and the use of

facilitates future location of the section, and pointers to the section (see also 4.2.3). A URI pointing to a directory should either resolve to a default file (as set in the server), a useful directory listing (for the target-user communities), or have a clearly identifiable page for further information. The name of the default page for a directory access is defined in the server configuration. The default page should be named default.htm, index.html, or home.html. The primary navigation environment should be presented when the default name within a directory is used. The REDIRECT header tag can be used to manage navigation. Issues related to navigation by people with disabilities have to be considered (visual or motion impairments particularly). a) All links shall work correctly. b) It shall be easy to navigate from any Web page back to the home page (e.g., a button should be provided to return to the home page every 1-2 screens). c) Links to “under construction” pages should be avoided.

The class designation “duplicatelink” should be used to designate additional navigational links which duplicate one on the page. One instance should not be designated a duplicate link. This allows style sheets to hide these redundant links from users where this may be a distraction (especially for aural presentation). Note the navigation requirements and recommendations in 4.2.7, many of which improve ease of use as well as accessibility.