Proposed Technique for 2.1.2

For 2.1.2 - Ensure extended DTDs are accessible

New document types are constantly being developed, and in many cases offer
improvements to the structure and utility of web content. In implementing
a new or extended document type it is important to ensure that a tool is
not removing access to information which had been inherent in the base
document type.

An example of a document type which contravenes this checkpoint is a
FRAMESET (link to w3c frameset.dtd) used without NOFRAMES - it precludes
access to the underlying information, whereas NOFRAMES provides a means to
access the information contained within the FRAMESET.

The same can apply to a reduced DTD. For example, producing a DTD which
did not include the ALT attribute for IMG, or effectively working to such
a DTD by not implementing a means to include the attribute compromises the
accessibility of any included IMG elements.

Charles McCathieNevile

Received on Monday, 5 April 1999 15:48:09 UTC