At present, there is no documented policy on the format of version strings for DM software releases. While researching the historical usage of version strings as part of improving the documentation of the science pipelines release process, it appears that (at least) 2-4 component version strings have been used in the past, presumably with varying semantic meaning for each field. Eg., lsst/afw has the tags 3.6.0, 184.108.40.206 and 16.0 In addition, there isn't any rule that requires the versions strings to increment as sequence of positive integers. I suspect most DM devs would be uncomfortable with the next major release being versioned as 99.88, followed by -47.-32, followed by foo.bar.baz.
In the interests of having a well-defined and non-ambiguous policy going forward I propose that semver 2.0.0 be adopted for versioning publicly released DM software. This policy would explicitly not apply to 3rd party software which is redistributed by DM nor DM producted software which is not formally versioned (utility scripts, etc.). Per package waivers to the usage of semver 2.0.0 would be requested via RFC.