> Abstracts are clearly metainformation in the general sense, but they seem,
> to my taste at least, a bit heavy-duty for a HEAD request. (Do we really
> want large HEADs to be routinely larger than small documents?)
HTML+ includes the ABSTRACT element for this. The "Summary" HTTP
header should therefore be reserved for a brief description.
At some point in the future we may wish to extend HTTP
to allow clients to request named portions of the document.
Right now the #ID suffix is interpreted by the client, but there
is now reason why with a suitable HTTP method (e.g. "EXTRACT")
the server couldn't extract the contents of the named container
and send that rather than the entire document.
It would be nice if the document fragment could be specified stuff between two
arbitrary points in a document, rather than relying exclusively on everything
to be named.