SBVR16 — Use of morphological variants of terms is inadequately addressed

SBVR apparently assume that business terms are composed of natural language words, and that those words may have multiple morphemes that are nonetheless the same word and the same term. That is, a vocabulary term like 'purchase contract' may also have the form 'purchase contracts', and a vocabulary term like 'is owned by' may be expressed as 'has been owned by'. But SBVR says nothing about any of this in defining 'designation' or 'signifier'.
When a signifier for the same concept is in a formal language like OWL or CLIF, this idea of multiple morphemes is not (usually) part of the language syntax. So this should be carefully addressed.

For the SBVR Structured English language, Annex C.1 explicitly says that these alternate morphemes are "implicitly available for use", which may mean they are treated as equivalent, or just that they are recognized as uses of the same designation.

In natural language, such morphemes carry additional meaning , e.g., plurality or tense or mood. And a morphological variant of the same designation may or may not carry additional meaning, This is important, because SBVR examples assume that plurals are conventional and irrelevant, but the Date Time Vocabulary says that the use of verb tenses in natural language conveys indexical time intent. That is:
'John is in London' and 'John was in London' have different meanings in English. Do they have different meanings in SBVR SE?
And if so, do they always have different meanings? Natural language convention requires that a statement that dates a past event uses the past tense, e.g., 'John was in London in 2008.' Is it meaningful in SBVR SE to say (in 2012) 'John is in London in 2008'? And does that mean a different proposition from 'John was in London in 2008'?