Can XML be documented using Doxygen, Sandcastle, or other documentation generators?

Question

I am currently using Sandcastle, Doxygen, and JavaDoc to generate documentation for code I have written. Is it possible to document XML schemas using these packages? If not,

Answer 1

I've just started using XML Schema Documenter which integrates with Sandcastle Help File Builder and its a great combination for my needs which are a .NET plugin framework that has XML based configuration.