The Attributes section of this document describes additional restrictions on strings in attribute values — in particular, restrictions for the following cases:
#" character, followed by a string which exactly matches the value of the
nameattribute of an element in the document with type type.
0—9, optionally prefixed with a "
e" character or "
-" character or "
Zin the date/time syntax must always be uppercase
For documents in the
character set name
given in a
labeled as “preferred MIME name” in the IANA
Character Sets registry
if there is one; or if none of the
fields are so labeled, a
Name field in the registry.