This comes out as two questions, the way I see it:
#1 Are these glyphs in the character set specified by HTML?
#2 Are these idioms available in the HTML markup language?
The answer to #1 is no, not really: The character set for HTML 2.0,
ISO8859-1, has an open-single-quote is at position 96, and a close
single quote at position 39, just like ASCII, though in some fonts,
these don't match nicely. There's also the double quote character at
position 34.
But if you were happy with those, you probably wouldn't be asking
this question...
The answer to #2 is no, at least not yet. The "sgml-happy" way to
write these is with entity references from the ISOnum entity set (I
think...):
<open-single-quote> => ‘
<close-single-quote> => ’
<open-double-quote> => “
<close-double-quote> => ”
These entity names are not defined in HTML 2.0. If we intend to
expand the character set of HTML to include such characters, it
makes sense to include the entities. But if we're just going
to map these names in to ISO8859-1 text strings, then I'd rather
not bother. I'd rather see folks write:
``a quote''
than
&rdquot;a quot&ldquot;
in that case.
This doesn't preclude a peice of software from scanning the text for
occurrences of `` and '' and replacing them by something that looks
better on a Mac, for example. (Just don't do this inside PRE.)
Dan