[tei-council] Another issue with @pattern
James Cummings
James.Cummings at oucs.ox.ac.uk
Sun Jun 7 18:47:51 EDT 2009
All of the examples of pattern so far have been namespace agnostic.
Is it worth specifying that namespace local prefixes are relative to the
document in which the pattern appears?
<certainty pattern="//figure/svg:*" locus="value" degree="0.2"/>
Since the TEI namespace is declared as the default namespace for any TEI
document it has no local prefix. So here I'm talking about the
certainty I have about the encoding of SVG elements I've embedded inside
TEI figure elements.
Where @pattern differs from using an XPointer in @target, is that in
order to talk about TEI elements by name in an XPointer you must declare
the namespace that you are talking about in the XPointer itself which
creates a very verbose string much longer than the examples where we've
used fragmentary @xml:id references or asterisks.
But the benefit of this in the @target attribute is that it remains
consistent to some degree when that document (or part thereof) is
embedded inside another.
Let's say we have a certainty pattern of //title. Inside a TEI document
where the TEI namespace is default this creates no problem. If we then
embed that document inside a METS containerization we might end up
pointing to title elements we didn't intend to. I'm not trying to shoot
down an idea that I'm partly responsible for encouraging, but I do think
we need to be careful that we aren't ignoring namespace problems. We
can do this by including some examples that point to named elements
rather than just attributes or asterisks. Moreover it would be a very
good idea to include a bit of prose either in the chapter or @pattern
spec which says something akin to:
"Elements which appear in the pattern with no local namespace prefix are
assumed to be in the TEI namespace since that is the default namespace
for TEI documents. Other local namespace prefixes used in a pattern must
be declared in the document in which the pattern appears. Care must be
taken when embedding TEI documents inside others where the TEI namespace
is no longer the default."
Except maybe phrased better.
-James
(Devil's advocate for hire)
--
Dr James Cummings, Research Technologies Service, University of Oxford
James dot Cummings at oucs dot ox dot ac dot uk
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