Sequence <was> Access Languages ...

[Rick Jelliffe]

> From: Mark L. Fussell <fussellm at alumni.caltech.edu>

> I am not saying sequence is unimportant, but I think SGML is overly 
> focused on it (from an IM perspective) because it comes from a 
> paper/linear background.  Information is rarely linear: it is only time 
> that is, which has caused some media [and the humans who use them] to be 
> (mostly) linear also.  It can be difficult to break that linear 
> assumption when it doesn't apply if your tools keep reinforcing it.

But do you think HTML would have become a popular markup language if its DTD
was like this?

<!ELEMENT html 
	( h1*, h2*, h3*, p*, I*, table*, tr*, td*, th*)>


This is reductio ad absurdum of what you are saying.  A DTD where all
sequence information is made explicit.

In such a DTD, all the elements would have IDs, and either some
external specification to set the sequence/containment, or 
a "next" IDREF attribute.   

SGML is not overly focused on sequence.  Sequence is such a basic
property of text that having to always mark it up explicitly is just 
bizarre.   

Of course boilerplate text can be removed and added. And of course 
chunks in one part can be usefully reflected into another part. 
But sequence is important because it is a prime property of language.
Databases contain words and pictures and various fragments.  However
SGML/XML must be a format to allow these to be placed as cohesive
language-mediating documents.

If people just want a database dump format for nice relational tables,
comma-delimiter formats are available and attractive.  But when they have
text which they don't want to have desequenced, SGML/XML can be useful. 

I think the other big trouble with trying to view SGML/XML as a poor database
dump format, is that when you get too far from a markup paradigm, you 
have to involve programmers rather than writers.  Just folks can write
HTML, at a pinch. If you go too much to a database mentality, you move
to requiring custom-tools for data entry, rather than simple text-editors. 


Rick Jelliffe

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