Status of the old SSN and the alignment to the new SSN

Dear all,

(SOSA is not in the scope of this discussion)

I would like to better understand your opinions on the transition from the
old SSN to the new SSN:

The URL of the old SSN ontology will redirect to the location of an OWL
ontology that :
 a. entails the old SSN ontology unchanged;
 b. entails the old SSN without the DUL alignment, but completely
disconnected from the new SSN
 c. entails the old SSN with the DUL alignment, imports the new SSN, and
contains the alignments between the old terms and the new terms;
 d. entails the old SSN without the DUL alignment, imports the new SSN, and
contains the alignments between the old terms and the new terms;

In case of (b), then:
 1. where is the document that contains the alignment between the old terms
and the new terms?
 2. without this alignment, is it really true that old SSN data becomes
valid new SSN data?

In my option, either (c) or (d) should be true, and we should consider that
SSN is an ontology series as per [1]: SSN old is the old version, the new
SSN is the latest version, BUT there may be other versions in the future.
There are thus standard OWL metadata that should be considered:
owl:versionInfo (ok), and owl:versionIRI.

Best,
Maxime

[1] - https://www.w3.org/TR/owl2-syntax/#Ontology_IRI_and_Version_IRI