[REP] Data versioning

Hi all,

I have the following requirement in the Repository Requirements
document:

==== [DDR-DATA-VERSIONING] ====
(original text): The DDR MUST provide the capability to fulfil data
versioning, where data includes but is not limited to device
descriptions and their device properties.

(New text): The DDR MUST support versioning, either inherently or via
another system, of device descriptions. 

My questions are: How will this work in practice? Are there use cases
for having two or more valid/correct device profiles in existence for
the same device? Versioning implies a new value for a given property,
not a different set of properties. Or is this simply to provide a
rollback mechanism to a previous version?

Cheers
Kevin