1. OUT-OF-BAND resource, EMBEDDED presentation
-- Today's <FIG> and <IMG>
2. OUT-OF-BAND resource, EXTERNAL presentation
-- Today's <A HREF=...>
3/4. IN-BAND resources.
-- This has the same problem that <LISTING> and <XMP> have.
If the language of the in-band resource doesn't follow SGML
rules, then the figure has to be CDATA -- which is nasty, evil,
and wicked.
> I was considering, for instance, suggesting that multiple references be
> allowed in a hypertext link, such as
> <A HREF="http://somewhere/mypage.html" HREF="http://somewhere/mysong.mid">
> which would get these two resources either simultaneously or sequentially,
> and present them together.
Better by far would be to retrieve a single resource that has
Content-Type: multipart/mixed or one of the other multipart medium types.
That in turn raises an alternative to in-band resources; retrieve a
multipart resource that contains all the resources required to display the
document; tag each resource within the multipart with a URN, and reference
them by URN from the `main' document. The Enabled Mail model does
something similar for Safe-Tcl scripts; we could do worse than to
examine it closely. It's at
<URI:http://minsky.med.virginia.edu/sdm7g/Projects/Python/safe-tcl/>
--Kevin
73 de ke9tv/2, Kevin KENNY GE Corporate R&D, Niskayuna, New York, USA