Linking DTD's

Marcus Carr mrc at
Wed Apr 21 00:34:33 BST 1999

"Campana, Sal" wrote:

> Is it possible to nest DTD's?  I would like to build a DTD from smaller
> DTD's...Is this possible?

Yes, though you might have an easier time getting your head around it if you
look at it from the other direction. Rather than building a DTD out of
blocks, you might think of it as replacing blocks in an existing structure,
which has the effect of enabling or disabling other blocks. We used this
approach when we did the Australian CALS suite of 27 DTDs - start with what
is essentially a library of declarations and relationships and then use the
DTDs to specify variations from that structure. As David M indicated, this is
a bear to manage and requires parameter entities to be used throughout,
though we overcame this by writing an application that generated normalised
DTDs for applications and humans.


Marcus Carr                      email:  mrc at
Allette Systems (Australia)      www:
"Everything should be made as simple as possible, but not simpler."
       - Einstein

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