Re: [xsl] XSL-FO versus PostScript

Subject: Re: [xsl] XSL-FO versus PostScript
From: David Carlisle <davidc@xxxxxxxxx>
Date: Fri, 28 Feb 2003 18:59:06 GMT

> I asked why we should prefer XSL-FO over PostScript, since PostScript is
> more powerful. The reply was that PostScript didn't have the high level
> document features provided by XSL-FO. So now my reply is, TeX provides
> those high-level features, *and* it allows PostScript constructs that
> give the full power of PostScript to the user. 

Using PS tricks in tex though does seriously limit you.
There is a very nice tex variant pdftex which produces pdf directly
instead of dvi. Almost all latex documents work unchanged with pdftex
and produce pdf, but if they have used the pstricks package then
you can't really port them. _not_ having the full power of a PS
interpreter is exactly what makes PDF a more popular distribution medium
than PostScript.
Coming from latex to xml is all about sacraficing power (and typographic
quality, normally) in order to gain sensible authoring control
(to say latex does not have the concept of validation would be an
understatement:-) and cross platform portability. (It's a lot easyer to
generate html.pdf,MSWord,etc from a single xml source than a single
latex one)

Your comments about FO seem to me to be just part of that trend.

Having said that, while I am a supporter of FO, given that most of my
documents are English and/or mathematics (ie no vertical or
bi-directional text no fancy bordered effects) I would always
(at the moment) print XML via XSLT stylesheet to latex rather than 
to FO. (see the pdf versions of the MathML spec for example)
It's hard to know in my case though whether that's based on
a real unbiased assesment or just a product of having latex
somewhere burried deep into my subconcious after having worked on it for
15 years or so.

> Is there another reason
> to prefer XSL-FO?

FO is a formatter neutral specification of the design of your document.
If you only have one formatter in mind then portability is all cost and
no gain, but longer term it can pay dividends.
TeX users used to be happy to create in Knuth's words "beautiful documents"
and (La)TeX is ideal for that. But these days they also want less
beautiful but more interactive documents in html or pdf as well as on
paper. Having pushed TeX to its limits to try to achieve that kind
of multiple use, I appreciate that starting from somewhere else
has an appeal. Starting from FO has a lot more appeal than starting from
PS if you want to have a style language that can work in a "browser"
(ie online documentation system of some sort) and on paper
from the same source, and have it styled by different products
using the same stylesheet specification.


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