From the SOAP/Lite.pm file (line #349 in my version):

# Q: why only '&' and '<' are encoded, but not '>'?
# A: because it is not required according to XML spec.
#
# [http://www.w3.org/TR/REC-xml#syntax]
# The ampersand character (&) and the left angle bracket (<) may appea
+r in
# their literal form only when used as markup delimiters, or within a 
+comment,
# a processing instruction, or a CDATA section. If they are needed els
+ewhere,
# they must be escaped using either numeric character references or th
+e
# strings "&amp;" and "&lt;" respectively. The right angle bracket (>)
+ may be
# represented using the string "&gt;", and must, for compatibility, be
+ # escaped using "&gt;" or a character reference when it appears in t
+he
# string "]]>" in content, when that string is not marking the end of 
+a
# CDATA section.
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