Converts a
DTD.Dtd (ie the verbatim front-end representation) into a
DTM, which is a pure algebraic representation,
supporting XML name spaces and more appropriate for further processing.
Namespace mode must be activated explicitly, and prefices to namespace urls
must be added explicitly. (This can be done by a preprocessor, see e.g.
eu.bandm.tools.d2d2.base.Dtd2Ddf.)
If namespacemode true, all names are checked for one(1) colon (':') max, and for
defined prefices. If false, a colon is a normal character.
20180416:
xmlns:x="uri"
xmlns="uri"
muessen ignoriert werden, haben zur Zeit keine Auswirkung und werden als vordefiniert
akzeptiert.
LATER: Tdom must accept ANY namespace uri, iff the namespace uri is undefined.