space-separated URI references in HTML

Does someone know the list of attributes which allow or even "require" a 
collection of space-separated URI references in HTML4 or HTML5?  This 
has been previously discussed:

http://lists.w3.org/Archives/Public/public-iri/2009Dec/0033.html

In looking at the HTML4 strict and loose DTDs.

http://www.w3.org/TR/html4/sgml/dtd.html
http://www.w3.org/TR/html4/sgml/loosedtd.html

The 'archive' attribute of the 'object' element seems to be the only one 
mentioned as allowing a "space-separated list of URIs".

Best regards,
Chris

Received on Tuesday, 21 June 2011 19:25:21 UTC