This note has been in the HTML drafts for some time:
Note: The SGML declaration for HTML specifies SHORTTAG YES,
which means that there are other valid syntaxes for tags,
such as NET tags, "<EM/.../"; empty start tags, "<>"; and
empty end tags, "</>". Until support for these idioms is
widely deployed, their use is strongly discouraged.
So while strictly speaking
<em/nifty stuff/
is valid HTML 2.0 markup, information providers would be ill-advised
to use it.
In fact, empty start tags and empty end tags might have nasty interactions
with the "ignore unknown tags" convention. They'll probably stay
deprecated indefinitely.
Support for unclosed tags is easy, so it might get supported widely.
But I doubt that style of markup would be used.
Hmmm... looks like it's time to dig up my old HTML test suite and
start maintaining it again. For example:
Implementor's Guide: SHORTTAG feature test
http://www.w3.org/hypertext/WWW/MarkUp/html-test/implementors-guide/shorttag.html
Version: 1.1 Wed May 11 20:13:29 1994
Unfortunately, the test suite isn't set up for navigating or downloading
right now. I'll work on it...
Dan