The intention of this interface is to provide a generic means
by which Grammar objects may be created without parsing instance
documents. Implementations of this interface will know how to load
specific types of grammars (e.g., DTD's or schemas); a wrapper
will be provided for user applications to interact with these implementations.
Returns a Grammar object by parsing the contents of the
entity pointed to by source.
param
source the location of the entity which forms
the starting point of the grammar to be constructed.
throws
IOException When a problem is encountered reading the entity
XNIException When a condition arises (such as a FatalError) that requires parsing
of the entity be terminated.