RE: [xsl] Re: Overlapping structures

[Wendell Piez <wapiez at mulberrytech dot com>]

At 06:51 AM 10/10/01, Mike wrote:
> > <a>I said <z.start/>I will watch my ways</a>
> > <a><x/>and keep my tongue from sin<z.end/></a>
> >
> > Can somebody give an example to justify why such an ugly
> > thing might be necessary in
> > the first place?
>
>Because not all information is hierarchical. In particular, with text there
>are often several concurrent (overlapping) hierarchies. The most obvious is
>the section structure versus the pagination structure. But it's easy to find
>other examples: in Shakespeare, the boundaries of "speeches" (defined by who
>is speaking) overlap with the boundaries of "lines" (defined by the metre of
>the poetry).

Or, in narrative poetry, metrical lines vs. verse paragraphs (which 
sometimes divide in the middle of lines), vs. dialogue (which can overlap 
lines and verse paragraphs, while nesting in its own right), vs. rhetorical 
events such as epic similes, etc. etc. Not to mention pagination in 
different editions, textual variants and so forth.

(I know one reader of this list who is using XSLT to generate SVG 
depictions of the page collations, and forme works, of various printed 
editions of given historical texts. Your application of XML/XSLT is 
probably as arcane to him, as his is to you.)

Someone had it right who remarked that these are applications in which 
markup is used to describe or trace phenomena already observable in extant 
data (texts, artifacts), as opposed to creating new data with new 
structures already optimized for particular functions. In the latter case, 
you can sometimes engineer the multiple hierarchies away, or more commonly, 
simply decide they're not important enough to bother with. In the former -- 
an important use case for markup languages -- to engineer them away is to 
fail at your primary goal.

As for ugly, yea verily, and if anyone can come up with a beautiful 
notation cum data model that describes multiple hierarchies and supports 
XMLish "synchronous" processing (by which I mean something like "random 
access" to a structured data set) ... there are plenty of us who want to 
hear about it!

>  And if you mark up a document with change markings, the
>start/end of changed sections bear no relationship to the logical structure
>of the text.

Yup. Or what one might call a "vexed relation", since what is changed is 
often precisely that logical structure. Even worse.

Cheers,
Wendell


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Wendell Piez                            mailto:wapiez@mulberrytech.com
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