XML property-lists problem

[richard]

I'm trying to complete support of XML property-lists in GNUstep, and I've run
into a problem -

There are certain control characters (such as the escape character) that are
illegal in XML, yet legitimate to have in NSString objects.

How should these be encoded in an XML property-list?
Does anyone know how MacOS-X handles this?

Encoding an escape as  doesn't work for me - during parsing, libxml
automatically translates that to an escape and then barfs because an escape
isn't legal.  Perhaps I'm missing something in libxml, or perhaps that's the
way the xml standard works - I'm not enough of an sgml expert to know.

Any help appreciated.