Question/comment regarding minor versions of UBL 2 and explicit or implicit rules for compatibility

[Stephen Green <stephengreenubl@gmail.com>]

Nice to see that UBL 2.1 is coming along well.

Just a question regarding how it has been kept compatible with UBL 2.0:

Presumably the compatibility has been maintained at model level via
some rules of some sort but are these rules the fully published in the
latest customisation guide and if so, is that the one on the UBL TC home
page,
i.e. http://docs.oasis-open.org/ubl/guidelines/UBL2-Customization1.0cs01.pdf ?

If not, are rules for progressing from a UBL version 2.x to a version 2.x+1
going to be published?

My own opinion would be to favour such rules existing at some time, even if only
to complete the picture given by the UBL NDR, but also to aid future submitters
of model requirements in assessing what additions/extensions would be feasibly
for a future minor version of UBL and which would possibly break compatibility.

Best regards

Steve
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Stephen D Green