RE: [xml-dev] Elements vs. attributes was: Are people really usi ng Identity constraints specified in XML schema?

Len,

You did indeed get the address idea right.  CAM allows you to customize the
layouts and tags to the local community - while retaining references to the
global dictionary definitions.  This is much cleaner than namespaces BTW.

The UPU has this use case.  In the CAM tutorial we show different address
formats - US street, US APO, and Canadian - all co-existing in the same
template.  This is immensely useful for international mail authorities trying
to automate address data exchanges between systems.

OASIS CIQ has also defined this uber-dictionary approach.

This also touches on versioning - you can have the one template handle versions
too.  And you can version at the element and attribute level - this is vital. 
Everyone thinks of versioning at the schema level - but in reality you need
versioning down atomically within the schema.  CAM fully supports versioning at
that level, and also using registry to augment that.

One other thing - versioning of CAM engine itself - and compliance checking
levels support by engine - yes - we do both.

BTW - another great benefit of CAM is that it is agnostic to the element /
attribute thing - you can treat them interchangably - and define rules and
semantics freely against - no restrictions - (caveat: within limits of
wellformness rules for XML).

So - in summary - 

o substitution sub-structures - check
o decoupling of tagnames to semantic meaning - check
o semantic referencing without need for namespaces - check
o versioning - structure and atomic levels - check
o registry supported versioning - check
o link from structure and rules to CAM version / level - check
o agnostic element and attribute handling - check

o Form level processing - (I noticed you sidetracked into this!) - no - we do
not do what XForms and XFA is designed to do et al - but we can generate form
markup given a form template - that's just rendering, nothing else.

Cheers, DW.
======================================

Quoting "Bullard, Claude L (Len)" <>:

But the flexibility of XML is that it can be heterogenous. . . and how to
understand when you will get what structure is the purpose of attributes. .
. so the more context sensitive XML modeler (who understands the
requirements first) might use:

<address country="us">
    <street />
    <city />
    <state />
     <zipCode />
</address>

for US address, and the the following for UK addresses:

<address country="uk">
   <buildingName />
   <street />
   <city />
   <postalCode />
</address>

I am not aware of a way to use Schema to enforce a substructure based on a
value in an attribute, but from the short look at CAM that I have done, this
seems to be exactly what it was designed to do. . . combine snippets of
variants together into a complete document that is very context aware.
David, did I get that right?