>> So in the end you come up with so many approaches to express similar structures. Expressiveness and flexibility are good so that you can define configuratio

>> So in the end you come up with so many approaches to express similar structures. Expressiveness and flexibility are good so that you can define configuration to meet the needs of the system or application you are building. XML Schema, Relax NG, etc. can be used to specify how the XML configuration should be structured, limits on data types, required versus optional configuration items. As I said before, XML gets a lot of flack for being verbose, ugly, and complicated, but it is mature, widely-supported, and might be worth considering depending on your needs.