xml-dev - Re: xslv updated

[Rick JELLIFFE <ricko@geotempo.com>]

Sebastian Rahtz wrote:
 
> The trouble is,  to go back a week or so, there is insufficient
> evidence that XSL FO *is* all-encompassing. If you reject it in favour
> of XSLV for simple jobs, we have to be very sure that its up to the
> really serious design/typesetting jobs. Which it does not appear to
> me, and I am sure the XSL WG would agree that they have made
> compromises already.

I cannot find any posting that relates to this. I can see Marcus Carr's
thread on whether FOs represent a good architectural approach, and also
the recent one on what is the most appropriate level, and also one
mentioning aural stylesheets.

But nothing anywhere actually specifying any hard details. What features
are missing from XSL-FO?  Perhaps Sebastian could give some details: I
for one would find it useful to have some idea of what is missing or
where they have gone wrong. 

It seems to me that there is nothing stopping fairly smart systems being
built under XSLFO. From vague memory, it seems that the biggest design
decision is whether to follow FOSI (an old DOD stylesheet language
written using instance syntax which allowed expressions to query the
current page position: this required tight coupling with the formatter
so only ArborText really implemented it) or DSSSL (keep a layer above
the breaking routines/paginator; sacrificing the ability to test current
page position forces more declarative nature {e.g."keep-togethers"},
reduces expressiveness, sharply increases retargetability.)  

(As for no quality typesetting being done with DSSSL (or near dialects),
I am sure that Uniscope in Tokyo had good material to disprove that. I
have seen it.)

Anyway, features required for capable typesetting vary according to
region: any system that cannot do ruby could not be regarded as a
quality system in Japan or Taiwan, for example.  Similarly requirements
vary for the material used too: for typesetting yellow page telephone
books (i.e. with display ads), according to one contact it is difficult
to get a good result without 4 page lookahead for determining which
pages floats should go on.  I would not expect XSL-FO to provide someway
of setting the lookahead for optimum page-floatation: that should be an
implementations decision for vendors to diferentiate their products.

Rick Jelliffe

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