Well-engineered Web sites shall include an index of all pages relevant to the target audience. A site may have more than one such index if there are distinct target audiences. The site index shall be accessible, following the requirements of 4.2.7, and should be provided in plain text format.

Web indexes maintained within a managed site shall consider the implications of referencing pages beyond the maintained responsibility of the site. Such pages may vary in availability, size, consistency of style, accessibility, correctness, timeliness, human language or other requirements of the managed site. A similar distinction may be applicable to any pages indexed which are not managed Web pages adhering to the site’s guidelines. Contractual arrangements with external site managers may be appropriate to address requirements of the managed site. Maintenance of bibliographies of offsite references may also be appropriate. Users may expect site index/search results to access all appropriate content and not content from outside of the site.

If the search results contain references from outside the Web site, such site references shall be listed separately from the references within the Web site, and shall be clearly identified as being external to the Web site.