Re: DTD's

[Eric Bohlman <ebohlman@earthlink.net>]

5/17/01 11:42:52 AM, Sandra Carney <scarney@endocardial.com> wrote:

>Hi,
>  We have a question about the necessity of DTD.  There are folks
>  among our developers who postulate that so long as the document
>  is well-formed, we don't need DTD's.  So far, so true.  However,
>  might this pose a quality problem later on especially if you want
>  to limit what are considered legitimate tags in the document?

If more than one person is going to write code that has to process your documents, or generate your 
type of documents, or if more than one person has to create your type of documents by hand, or if 
only one person is involved but there isn't concrete evidence that he/she can survive being run over 
by a truck, then you're going to need some sort of formal and precise description of how your 
documents are supposed to be structured.  Writing a DTD or other type of schema (XSD, RELAX, TREX, 
etc.) is usually a far easier way of getting this description than writing a tedious prose 
description of which elements can be contained where (you still need to write a prose description of 
what the various structures *mean*, but this is far less tedious).  If you try to go the purely 
informal route, then you're going to wind up with Person A writing code to generate documents that 
can't be processed by the code that Person B wrote, with both Person A and Person B claiming that 
they did the job correctly and the other one didn't.  If your documents have to cross organizational 
boundaries, such problems are tremendously magnified.  IMHO, the main value of a DTD or other schema 
isn't in enabling machine validation of documents; it's in making sure that people are all on the 
same wavelength.