> -----Original Message-----
> From: Rick Jelliffe [mailto:ricko@allette.com.au]
> Sent: Monday, April 27, 1998 11:53 AM
> To: xml-dev
> Subject: Re: XML-Data, "&" and inheritance
> Also, I cannot see why XML-data does not use regular expression syntax
> for specifying content models. I can see many good reasons for using
> elements for defining types, but not for using elements for
> each part of
> a content model. I note that the OmniMark program SGML2DTD, which
> converts DTDs into a form quite similar to XML-data converts a
> certain company's (XXX) version of DOCBOOK DTD from 178K to
> about 600K. This seems an enormous overhead. If this is so, then
> XML-data schemas (as they are now) are really only suitable
> for smaller
> DTDs (i.e, those belonging to databases), for web use.
>
I think there are good reasons to not use regular expression syntax:
1. It is not easily read by those who have not been working with it for many
years. I think millions of HTML authors can figure out XML-Data's verbose
syntax much more quickly than they can learn regular expressions. I think
this makes the verbosity worthwhile.
2. I can use the same XML tools to deal with the XML-Data schema documents
as I use to deal with my other XML documents. If regular expressions were
used for even part of the syntax, this wouldn't be the case, and I'd need a
regular expressio parser.
3. A large schema built from scratch in XML-Data should be able to save a
lot of space by using inheritence to avoid copying large sections of similar
schema information.