The GlueX experiment has adopted a policy that all shared data should be described in xml. A set of tools has been developed that enable programmers to respect this policy without the overhead of having to do building and parsing of xml documents in user code. The data are described in terms of data model structure like an xml document. The rules for building such model documents is called the HDDM specification. Once a user has described the data model in xml, tools are provided to translate the model into c structures, xml schema, and a general purpose i/o library.
