I would like to join Elliotte Rusty Harold, James Clark, Tim Bray, Michael Kay and David Carlisle in deprecating or being dismayed by XML 1.0 (fifth edition). The fifth edition loosens up rules about characters that can appear in names. This means that anyone who actually creates such documents will find they are not accepted by approx 100% of XML parsers out in the world, as of now. Guaranteed non-interoperability in the name of better inclusiveness.