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Subject:Re: Clarification on XML Concepts: Structure From:Tim Altom <taltom -at- SIMPLYWRITTEN -dot- COM> Date:Sun, 13 Jun 1999 16:11:05 -0500
If I may be permitted some clarification of my own...
>Think of XML as you would a database: you start with a DTD (Document
>Definition Type)<remainder of para snipped>
This is a description of valid XML. There is another form of XML that's
looser and free-form: well-formed XML. Well-formed XML doesn't require nor
use a DTD.
>And, (just like with a database), XML content is no more "optimized" for
>online delivery than information in database tables is "optimized" for
>use in forms and reports. XML content, like database content, is
>optimized as DATA so that you can control it. You are free to use your
>imagination as to how the content will be delivered.
This is so and needs more emphasis still. XML is not, not, not, not an
online delivery format. It's a data format. Its greatest use will doubtless
be in network delivery of data, but it doesn't have to be used exclusively
for that. You can save entire Word or FrameMaker documents as XML, or you'll
be able to within a couple of years.
>I would caution against lumping XML and HTML together, because although
>they work together (you don't have one without the other) they are much
>different CONCEPTUALLY. Having logged long hours doing database
>development, I see documentation experts facing the same challenge that
>confronts those who are new to relational design--how to mentally
>separate content from formatting. This is exactly what XML does, because
>it lets you separate content from HTML formatting. Not an easy concept
>to grasp, I admit, but on essential to future document development in a
I'd rephrase this and say "Separate structure from formatting and content
both". XML does not involve content or formatting.
You can have a perfectly valid and parsed XML document with nothing between
the opening and closing tags. Silly, but valid. What you WILL have is a
structure that doesn't vary from one environment to another. My XML
structure is your XML structure, courtesy of the DTD we share. Another form
of document, another DTD, another structure. But you'll determine the
formatting you want at your end, while I determine my preferred formatting
here. Somebody else can insert the content at my end. Three different
things, three different injection points.
Valid XML, like SGML, is structure incarnate, structure that is actually
present in the abstract. Content is, in reality, optional, and so is
formatting. Structure exists independently of both.
Well-formed XML is another matter and is merely parased as a kind of
"super-HTML", or an HTML that's self-defining, but has structural elements
within it. Not nearly as rigorous as valid XML.
Simply Written, Inc.
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