Stabilized Technical Report
UTS #22, "Unicode Character Mapping Markup Language"
has been stabilized:
There are no plans to ever publish another update for it.
The last version can be found at
The discussion of issues in UTS #22 remains relevant,
although the specific XML format is not commonly used.
For example, the Unicode
ICU project uses conversion data files in a different format, as does
the W3C Encoding specification.
In addition, newer resources such as
UTR #36, Unicode Security Considerations,
the Unicode Standard Section 3.9, Unicode Encoding Forms
(especially definition D93 Encoding form conversion), and
the Unicode Standard Section 5.22, Best Practice for U+FFFD Substitution,
expand on many of the issues discussed here.