Elliotte Rusty Harold as usual, has been making a ton of sense on xml-dev about binary XML, while others persist on throwing the baby out with the bathwater (after having muddied the water), so they can save a few CPU cycles or bits on the wire, while remaining on message as regards interoperation. Years from now, if XML itself becomes a useless quagmire of incompatible binary codecs, you can look back and admire the stunning naivety of it all. Interoperation, even basic interchange, requires constant maintenance and effort. Managing localized and short term interests in a networked system is effectively managing entropy. If there is a better optimal means that XML 1.0 for doing this, I'd like to hear about it. Nonetheless, there was this: Additional, fine. (Think XML Namespaces, XSLT, XML Schema, XML Query Language, xml:id, etc.) none of which in any way alter the basic nature of XML. - Elliotte Rusty Harold Elliotte's rarely wrong, but he's wrong here. XML Namespaces do alter the basic nature of XML - enough to be backwards incompatible. Just try mixing non-namespaced and default namespaced markup and see for yourself....