Use of UTF-8 and UTF-16

["Paul Spencer" <xml-dev@boynings.co.uk>]

I see many XML-based interoperability projects that specify whether to use
UTF-8 or UTF-16 for Unicode character encoding. One will usually result in
smaller documents/messages that the other (broadly, UTF-8 is better if the
character set is mainly ASCII, and UTF-16 is better otherwise). However, I
see no reason to specify this in terms of interoperability since XML
processors must support both. Obviously, if you are using encodings other
than these, they will need to be specified. Am I being stupid here (after
all, it is Friday afternoon), or is there ever a good reason to specify
which to use other than for document size reasons?

Paul Spencer