PROPSAL: XSchema declarations and constraints

Simon St.Laurent SimonStL at
Wed Jun 10 20:06:36 BST 1998

Andrew Layman asked:
>Could someone provide a crisp definition of what you mean by the term
>"metadata" in the context of this discussion. 

To be honest, I think this is a discussion we should avoid, and answer only in 
practice.  The 'metadata' swamp is unmapped, yet well known to be enormous and 
filled with quicksand.  Rather than wandering into this swamp on foot, I'd 
prefer that we build roads into it, stiffening the ground below us as we move 
from place to place. 

>A commonly-offered definition ("data about data") is vacuous in
>actual practice, if not conditioned by further information, since it
>indicates no operational or essential distinction between metadata and any
>other kind of data.

'Data about data' may be vacuous, but also has the benefit of accuracy in its 
very being vacuous.  In my (admittedly limited) world, practice is the only 
way to define such mushy concepts.  "What is metadata?" is meaningless; "Is 
that metadata?" can lead to interesting discussion.

Funny, I used to really love philosophy... but always hated epistemology.

For right now, the two forms of metadata encoded in an XSchema are:
1) Acceptable structures for elements and attributes (one kind of constraint)
2) Documentation for elements, attributes, and the XSchema itself.

Paul's proposal appears (to me) to be about making certain that our 
constraints are extensible, which seems like a laudable goal we have some 
chance of building into our structures.  Its relationship to metadata seems 
less important to me than its relationship to the extensibility of XSchemas.

Simon St.Laurent
Dynamic HTML: A Primer / XML: A Primer / Cookies

xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at
Archived as:
To (un)subscribe, mailto:majordomo at the following message;
(un)subscribe xml-dev
To subscribe to the digests, mailto:majordomo at the following message;
subscribe xml-dev-digest
List coordinator, Henry Rzepa (mailto:rzepa at

More information about the Xml-dev mailing list