Re: DTD extensions

Terry Allen (
Mon, 16 Aug 1993 08:15:50 PDT

> From: Lou Burnard <>
> Subject: DTD extensions and modifications
> Should there be one DTD only for HTML?

There CAN be only one DTD for HTML+ (forget about HTML, that's frozen)

> What if my browser wants/knows
> about/must have some elements that yours doesn't?

Write an extension to the DTD.

> What if I want to tag
> my documents in some language other than English?

Why? tags are markup, not content.

[TEI stuff, all appropriate for TEI but not really needed here:]
> All elements in the TEI dtd are declared indirectly.

This is only indirection, with provision for extension. It
doesn't mean having multiple DTDs.

> All(most) elements in the TEI dtd are assigned to a class, ...

This is about restricting contents to particular contexts, coming
in HTML+.

> Every element declaration in the TEI dtd is bracketed by a marked
> section named for the element itself, the value of which is by default
> 'include' but which can be changed to 'ignore' in the DTD subset. So, to
> remove the current definition for 'blort' (either because you don't want
> to allow blorts or because you want to substitute your own definition
> for them -- not a good idea, but it happens --) you just bung a
> <!ENTITY blort 'IGNORE'> into your dtd subset and kiss those blorts
> goodbye (sorry Sebastian)

Sure, you can cut down your HTML+ DTD; that won't hurt anything. You
don't need the TEI method to accomplish that.

> Every elements in the TEI dtd is defined in one 'tagset' or dtd
> fragment.

A way to encourage modifications; why do we need this for HTML+?


Terry Allen  (
Editor, Digital Media Group
O'Reilly & Associates, Inc.
Sebastopol, Calif., 95472