Compatible UBL Customization
* An existing UBL type can be modified to fit the requirements of the
customization through XSD derivation. These modifications can include
extension (adding new information to an existing type) and/or refinement
(restricting the set of information allowed to a subset of what is permitted
by the existing type).
This just means to me: A compatible UBL customization would be one which
reused the UBL schemas, which did not add any new types to a UBL namespace,
and which followed the XML Schema spec.
This is given as being the non-compatible customization:
"There are two important types of customization that XSD derivation does not
allow. The first can be summarized as the deletion of required components
(that is, the reduction of a component's cardinality from x..y to 0..y). The
second is the ad hoc location of an addition to a content model. There may
be some cases where the user needs a different location for the addition
than the one allowed by XSD extension, which is at the end of a sequence."
I seem to remember there was a statement somewhere in some document on this
subject that one could also not just rewrite the schema in the following
manner:
One has a number of types that in UBL proper are strings, but in the
customized schemas are required to be a list or some regular expression
restriction of string. The customizer rewrites the schema and makes the
changes. Isn't there a statement somewhere that this is disallowed?
Or is the disallowance of this method wrapped into the definition of what is
a Compatible UBL Customization.
