[sc34wg3] Association items

Murray Altheim sc34wg3@isotopicmaps.org
Sun, 12 Jun 2005 22:59:57 +0100

Lars Marius Garshol wrote:
> * Murray Altheim
> |
> | I realize that Lars Marius has argued that association type (along
> | with other things) should not be optional in XTM, whereas I would
> | suggest that XTM be left alone and push this kind of thing into a
> | proper constraint language operating at a higher schema level -- the
> | XTM DTD is really only meant to express syntax-level constraints.
> What we agreed in Amsterdam (this year) was to leave XTM alone, but to
> require an association type in TMDM. However, TMDM will define a PSI
> for untyped associations that is inserted when no explicit type is
> given. Thus we avoid the ugliness of association.[type] sometimes
> being null, yet we keep backwards compatibility.
> The implication is that we consider all untyped associations to have
> the same type, but this seems fair.

When that PSI becomes available, could you forward an announcement
to the group? I'm currently using a similar PSI within Ceryle and
would like to either add it as an equivalent subject or substitute
it (depending on where I am in my "product lifecycle" when the PSI
becomes available). Thanks!

> Anyone wanting to disallow such associations should be able to do so
> by means of TMCL.

Yes, this seems like the correct place for such a constraint.


Murray Altheim                          http://www.altheim.com/murray/
Strategic and Services Development
The Open University Library
The Open University, Milton Keynes, Bucks, MK7 6AA, UK               .

       The moment you come to trust chaos, you see God clearly.
       Chaos is divine order, versus human order. Change is
       divine order, versus human order. When the chaos becomes
       safety to you, then you know you're seeing God clearly.
                                               -- Caroline Myss