Seems to be an odd grey area.
Nothing grey at all. If you are training it is PUT; if its a a test and you pass, its P1S and your log is signed by the examiner. You cannot exercise the privileges of the rating until you have a licence with that rating in PartXII and a Certificate of Test which is issued with the rating. You could fly and log solo flight in the interim period provided you are authorised by an instructor.