My immediate take on this is:

version-number is only used once, and seems relevant in that context.

previous-versions refers to functionality provided by Windows to roll-back files; this tag is valid.

versions is already a synonym of version, so doesn't really exist.

version (and so versions), along with versioning, should probably all be synonyms to version-control. However, there's going to be a manual retagging job to be done here as I suspect many of the current questions are misusing them, but some will need saving.

My immediate take on this is:

version-number is only used once, and seems relevant in that context.

previous-versions refers to functionality provided by Windows to roll-back files; this tag is valid.

versions is already a synonym of version, so doesn't really exist.

version (and so versions), along with versioning, should probably all be synonyms to either version-number or version-control, which are much more explicit. However, there's going to be a manual retagging job to be done here as I suspect many of the current questions are misusing them, but many will need saving.