(Brit) an unnamed person: used in team lists, etc, to indicate a place that remains to be filled
a.o.c. Latin anno orbis conditi (the year of the creation of the world)
a.p.c.n. Latin anno post Christum natum (the year after the birth of Christ)
also APR, abbreviation of annual percentage rate, attested from 1979, American English.
a.p.r.c. Latin anno post Roman conditam (year after the foundation of Rome)