From D. H. , personell / fleet office and trng dept all have files which reference sen#. As it was continually changing it was becoming administratively difficult so now you keep the same number infinitum.
Must have a hard time filing stuff, as now there's double-ups with the seniority numbers. Have a look at the end of the -400 freighter lists and you'll see them starting again with #3, 4 etc (ASL guys?)
