Separation of formatting...

len bullard cbullard at hiwaay.net
Thu Apr 30 18:50:24 BST 1998


Sean Mc Grath wrote:
> 
> The "separation of formatting..."
> mantra is a big part of SGML/XML obviously.

Well, no.  It is a big mantra often recited by 
folks who apply SGML.  SGML does not care.  It 
is important to keep that distinction alive 
because otherwise one sinks into the "holiness 
of the page metaphor" debates.  Those debates usually 
end in a discussion of target granularity and 
searching requirements.  Pixel/raster memory 
does not care either.

> However, it works on a number of levels.
> 
> Here is a pieces of data marked up three ways:-
> 
> Version 1 : Purely Formatting Mindset (RTF)
>          "{\i Customer} Joe Bloggs \par"
> 
> Version 2 : SGML - Generic Markup
>         <p><i>Customer</i>Joe Bloggs</p>
> 
> Version 3 : SGML - Data Modelling
>         <Customer>Joe Bloggs</Customer>

> Somewhere along the line, people started thinking
> as in version 3 above. I have no idea when this
> started to happen. Anyone out there know?

The first large application of it that I remember 
was the US DOD Content Data Model for IETMs.  We 
did similar things in the US Navy CASS application. 
I used it for the US Army IADS DTDs after the 
CASS program moved on.

In many cases, it was to help the author use the 
editor more precisely by indicating in the menus 
what the precise content had to be.  As we used 
this approach, we found that it helped with 
searching and target granularity plus had excellent 
lifecycle characteristics, ie, less information 
is lost when one does not have to archive a 
down-translated chunk of information.

It suffers when one has to aggregate data from 
multiple sources without namespaces under a root.  For that, 
we have traditionally applied switch tags in the 
DTD, and while that works, it won't work automatically 
which I believe is the requirement for namespaces.  
 
len

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