Does the constraint mechanism allow removal of core elements?

I am putting together authoring DTDs for DITA topics.
One of the things that I would like to do is to constrain away elements that are meant for architectural extension rather than for authoring.
For example, it would be nice to remove <data>.
The DTD mechanics for incorporating this into the content model are straightforward: Out-of-the-box: < !
ENTITY % data "data %ut-d-data_option; "
> Constrained: < !ENTITY % data " %ut-d-data_option; "
> Is there a way in DITA 1.3 to declare this as a constraint? I suspect that there isn't. If that's the case, then I claim that there should be a way to declare this because it is a reasonable thing to do.

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Bob Thomas +1 720 201 8260 Skype: bob.thomas.colorado Instant messaging: Gmail chat (  ) or Skype Time zone: Mountain (GMT-7)