Why do we need to put a reference anyway? It is only to help the unqualified people in Tech Services & QA! When we certify either under JAA or FAA we certify that the work has been carried out in accordance with the requirements .......... The requirements are all work is carried out iaw the approved MM.
Some companies also require statements that function test carried out also. Just bull sh** form office wallahs.
I have seen many mechs with lists of ATA references which they quote but never refer to the manual, they don't get letters from QA even though they have not followed the correct procedures.