[netmod] YANG Versioning question - namespace version?

[Kent Watsen <[e-mail]>]

NETMOD WG,

I was recently asked why YANG module namespaces aren’t versioned.  For example, the “1.0” at the end of this URI "urn:ietf:params:xml:ns:yang:ietf-crypto-types:1.0”.  The stated concern was "because without this, then management of backward compatibility becomes a nightmare.”   

This convention was established prior to my becoming active in the IETF, but my guess is that the reason is because the YANG-module update rules in RFC 7950 Section 11 ensure backwards compatibility, and hence the versioning the namespace would have no value.  That said, the YANG Versioning effort introduces the possibility of NBC changes, which makes me wonder if this is something that should be discussed.

Thoughts?

Kent