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- From: Eric Bohlman <email@example.com>
- To: firstname.lastname@example.org
- Date: Wed, 27 Dec 2000 22:57:26 -0600
12/27/00 4:23:54 PM, bigbadz <email@example.com> wrote:
> I am fairly new to XML and trying to understand the difference between
> DTDs and schemas. Is one a subset of the other? What are the key
> objectives to each? Can someone briefly explain?
Strictly speaking, a DTD is a type of schema. Due to the limitations of DTDs
(such as the inability to impose any restrictions on the text content of
elements), various alternative schemas have been proposed. The best-known of
them is the W3C's XSD proposal, often (but perhaps unfairly) referred to
simply as "XML Schema." It's now in the Candidate Recommendation phase.
Other alternatives are Microsoft's XDR schema language and Murata Makoto's
Most of the limitations of DTDs become bothersome when dealing with "data" XML
rather than "document" XML. It's likely that DTDs will survive and still be
widely used for the latter types of applications.