Trang is a command line converter for XML schema languages. The
following languages are supported:

* RELAX NG (XML syntax)
* RELAX NG compact syntax
* XML 1.0 DTDs
* W3C XML Schema

W3C XML Schema is not supported for input.

Trang can also derive a schema from XML documents.

Trang will try to build human-readable schemas; aspects of the input
schema will be preserved as much as possible (including definitions,
spreading over files, annotations, and comments).