From: OXVAXD::LOU "Lou Burnard" 25-MAR-1997 11:47:00.87
To: MX%"[log in to unmask]"
CC: LOU
Subj: RE: Grouping (was: A couple of "minimalist" examples)
|
|I'd prefer to see a more generic but extensible grouping construct
|rather than a small or large set of very specific constructs, because
|no matter how large that set is, more will be needed. The SGML
|approach seems to be to hard code the predefined grouping constructs
|(and anything else) in a DTD without any runtime extensibility or even
|much composability. My SGML knowledge is limited, so that is mostly
|an intuition.
I think this is a mistaken impression. So far as I know, when one is combining
logical assertions such as "metadata fragment x applies to this resource" just
two options exist for interpreting any pair of such assertions: either they
both apply, or one applies to the exclusion of the other. I am
not aware of any other way of grouping pairs meaningfully -- if you are, please
tell us, and show why it cannot be reduced to some combination of these two.
As to SGML -- you can make it as tight or as loose as you want. The easiest
SGML dtd to write is one that says any element can be combined with any
other in any way you please -- but that does put rather a burden on the
application.
To make this a touch more concrete: if I get two metadata fragments that seem
to be saying something about a date, I need to know whether
(a) the two are to be interpreted together, for example as a date range
(b) one of the two applies in some situations and the other in others (e.g.
one is a publication date, and the other an expiry date)
I can't think of any third thing.
Lou
|