Updating DTDs, CLDR makes special use of XML because of the way it is structured. In particular, the XML is designed so that you can read in a CLDR XML file and interpret it as an unordered list of <path,value> pairs, called a CLDRFile internally. These path/value pairs can be added to or deleted, and then the CLDRFile can be written back out to disk, resulting in a valid XML file. That is a very powerful mechanism, and also allows for the CLDR inheritance model.
