This class is to hold all schema component declaration that are declared
within one namespace.
The Grammar class this class extends contains what little
commonality there is between XML Schema and DTD grammars.
This class customizes the behaviour of the util.NamespaceSupport
class in order to easily implement some features that we need for
efficient schema handling.
This class implements xni.grammars.XMLGrammarLoader.
It also serves as implementation of xs.XSLoader interface and DOMConfiguration interface.
This class is designed to interact either with a proxy for a user application
which wants to preparse schemas, or with our own Schema validator.