Questions about character sets and their encodings

[Mark Bartel <mbartel@xxxxxxxxxxxxxxxxx>]

I've been searching for resources on the web on character sets for
ASN.1 types, but haven't been able to find what I need.  Does anybody
know of such resources?

More specifically, my questions are:

        IA5String: I've heard this is just 7-bit ASCII, but is that
true?

        TeletexString: I understand that one can select different
character sets with escape codes; does anybody have the set of escape
codes and character sets they select?

        UniversalString: X.690 says that this is encoded in 4-octet
canonical form, which I would imagine is 4 bytes, big-endian.  Also, I
believe that the subset of the 32-bit space with the high 16 bits set
to 0 is equivalent to Unicode.  Am I correct in these assumptions?
X.690 says a bunch of things that I don't really understand (probably
because I don't have X.680) about character string types and their
encodings.  Also, what is the tag for UniversalString?  Does anybody
have examples of certificates with UniversalString values in the
Issuer or Subject?  I've heard that Microsoft certificates do, but
when I queried Verisign for Microsoft certificates they didn't.  I
couldn't get ahold of any Microsoft products that actually issue
certificates to check that possibility.

I know I could probably get the answers by ordering ISO/IEC 10646-1
and X.680, but from what I can see I'd have to do it snail mail.  I'd
rather not.

- Mark Bartel