You're right, Mike, in the context of the system that is the WWW, the
utterance of an <A href="foo">bar</A> invokes a specific system
behavior, and that behavior is the semantic. It's a useful exercise to
try to articulate the semantic of foo, so here's an attempt at it:
"foo is the stream of bytes that will be sent to your browser by some
server when you click on bar."
Note that "bar" has nothing to do with the semantic of foo, which is a
stream of bytes. It would be the same stream if "bar" were "zorp",
instead. "Bar" is just something to be rendered as a trigger that the
user can choose to pull, not more. "Bar" doesn't necessarily establish
any semantic, and even if it did, there's no disclosure of the semantic
universe in which bar has that semantic, so again, it doesn't establish
the "what" that you're referring to.
Now here are two exercises for you:
(1) In your XML document, you want to insert a reference to the
Constitution of the United States. This should be relatively easy,
since the Constitution is itself a document, XML itself is a
well-disclosed universe of discourse that is packed with symbols that
are unequivocally about information, and the Constitution can be found
in numerous places on the Web. Right. But it turns out not to be easy
at all. Remember that the Constitution is emphatically *not* a stream
of bytes. Nor is it any copy of its text, no matter how represented.
It is a social contract, considered from some perspective that, so far
anyway, is known only to you, since you're the one making the reference.
(2) In your XML document, you want to insert a reference to the Statue
of Liberty. Go.
Unambiguous non-interactive communication is hard to do.