/summa/TP/TPIII/TP_Q63:
We have now to consider the other effect of the sacraments, which is a character: and concerning this there are six points of inquiry:
(1) Whether by the sacraments a character is produced in the soul?
(2) What is this character?
(3) Of whom is this character?
(4) What is its subject?
(5) Is it indelible?
(6) Whether every sacrament imprints a character?