[html5] Multiple IDs for an element?

This is probably due to historical reasons (SGML?), but why isn't it (or shouldn't it be) allowed to use multiple IDs for a single element?

Wouldn't that be valid (concerning the understanding that an object might be unique not only in one, but several regards), and thus probably something that we could consider for HTML 5 (and CSS 3, too)?


  <h2 id="intro special" />

... covering a certain "introduction" annotation that is at the same time "special" (for example, including a foreword by a different author in a fictitious "article of the month"). Similar to classes, this could probably not only be formatted via "#intro" and "#special" selectors, but also by "#intro#special", for example.

Ad hoc, I see that change as an advantage concerning general understanding of "uniqueness" as well as an improvement when it comes to consistency. On the other hand, it likely imposes more or less severe compatibility problems.

This question and suggestion has almost certainly been discussed before, but I couldn't find any useful references except for a CSS test case that uses "id" and "xml:id" attributes on the same element [1].

[1] http://www.w3.org/Style/CSS/Test/CSS3/Selectors/current/xhtml/tests/css3-modsel-15c.xml

Jens Meiert

Those who would give up essential liberty, to purchase a little temporary safety, deserve neither liberty nor safety. - Benjamin Franklin.

Received on Tuesday, 24 July 2007 15:32:49 UTC