docbook definition still based on DTD?

["Robert P. J. Day" <rpjday@crashcourse.ca>]

  perhaps a silly question, but at the moment (as i read it), the
definition of docbook is generally presented as the official DTD.
however, there is also a schema for docbook and, given that schemas
can represent things non-representable in simple DTDs, will there be
a point where docbook (5.0?) can no longer be represented by a simple
DTD?  or has that already happened?

rday
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Robert P. J. Day                               Waterloo, Ontario, CANADA

            Linux Consulting, Training and Kernel Pedantry.

Web page:                                          http://crashcourse.ca
Twitter:                                       http://twitter.com/rpjday
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