pure XML

[Chris Despopoulos]

Please correct me if I'm wrong...  I've been out of the markup loop for too long.  But...

I remember in the old SGML days it was explained to me that SGML is a grammar, and not a language.  The same would hold true for XML. Each DTD or Schema makes a language -- a specific implementation of the grammar. So Docbook and DITA are very different, but both are (ostensibly) pure XML.  Further, DITA provides ways to extend DITA and still be DITA.  

Impure XML would refer to constructs in the markup that are not within spec. I suppose some vertical deployments of an XML system could rely on "impure" XML.  This would be viewed with horror by most people in the industry.  It seems to me it would be unwise as well.  The cost of relying on non-standard XML would ultimately outstrip the cost of complying with the spec (or so the theory goes).  A good candidate for impure XML could be the Microsoft Word XML, but even that might be pure, technically speaking -- even if the goal is to tie you to Microsoft Word when you use it.

Getting back to FrameMaker, I believe FrameMaker does express constructs that are specific to its own processing, but those expressions are within spec, and so the XML would be considered pure.  The practical question would be, can you properly render a document from FrameMaker-generated XML, no matter what process you use to render it?  In other words, is the FrameMaker XML tied so much to the proprietary system that it defeats the purpose of XML?  I believe FrameMaker does not tie you to a proprietary system.  But if you want to take full advantage of the proprietary FrameMaker system, then you can use the special, proprietary constructs.   

Of course, the devil is in the details. 



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ust to add to the mix.? I'm noticing also that companies, irregardless
of tool, customize their XML in some way that makes it become
'unpure'.? 

The files that I authored in Epic, that I thought
should have been very close to the open source version of XML, where
unreadable by the open source compiler.? I had nothing fancy, just a
heading, and a couple of paragraphs. 

I find it facinating.?
And it feels like there is the potential for some sort of fancy
doctoral study on this sort of thing.? How open source/industry
standard things become customized and particular to a company or group
of people. DocBook vs DITA included. Both are XML, but o, how different
they are.
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