XML trade off 1 - DTD vs XML Schema

Tim Bray tbray at textuality.com
Wed Jul 21 23:42:34 BST 1999

At 02:00 PM 7/21/99 -0700, MEdson at walldata.com wrote:
>So do you believe that both DTDs and XML Schemas are necessary?  Would you
>please elaborate on what advantage DTDs have over Schemas and if possible
>explain why DTDs were NOT designed to be written in XML?

DTDs are necessary because you need some formal way to describe (at least
part of) your data design.  They have their current syntax because the ISO 
committee that designed SGML thought it was better that way, and XML 
inherited them from SGML.  XML Schemas are said by many to be necessary for 
a variety of reasons, including most prominently datatyping and the use of 
XML syntax.

The most important difference between DTDs and syntax is that are here now
and work now and standardized now.  Admittedly one could wish for something
better but until it arrives DTDs are what we have. -Tim

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