[ubl-ndrsc] Ur type discussion

["Burcham, Bill" <Bill_Burcham@stercomm.com>]

Great to have you back Matt G.!  A few questions about the Ur Type position
paper
http://www.oasis-open.org/committees/ubl/ndrsc/current/draft-gertner-urtypes
V01.doc

** Ur-Types for All ABIE's or Just for "Message Types"? **

Is the proposal to have ur-types only for "message types" and not for all
the ABIE's?  The discussion around line 108 makes me think so.  If that's
the case then a user could specialize the Order (ur-type) so as to remove
the OrderHeader, but the user would be unable to e.g. remove the ZIP code
from an Address (ABIE) (assuming ZIP code was a Basic BIE Property of the
core UBL Address).

If I read that wrong, then is the proposal to have ur-types for all the
ABIE's?  In that case a user _would_ be able to remove the ZIP code from an
Address.  Such an Address would be "loosely" compatible in the terminology
of the proposal right?


** Inheritance Relationship Between a Type and Its Ur-Type **

The proposal around line 78 (in section 2 "The 80/20 Design Principal")
describes LCSC's decision to specify only the 20% of the structures
(components) that will suffice 80% of the time.  While the proposal doesn't
couch it in similarly quantitative terms, I'll volunteer that the
"specialization via XSD extension" described in section 1 "Type Derivation"
satisfies a similar equation, to wit, that type derivation will solve 80% of
the problem (with minimal effort).

Since section 1 "Type Derivation" sets out an XSD type derivation regime as
the dominant specialization mechanism (the one that we expect to suffice 80%
of the time), I wonder what the inheritance relationship will be between a
type and its ur-type.  Intuitively I thought that a type would derive from
its ur-type, but the proposal doesn't say so, and I can imagine certain
problems with that.


Regards,
-Bill