CCC 1304 Like Baptism which it completes, Confirmation is given only once, for it too imprints on the soul an indelible spiritual mark, the “character,” which is the sign that Jesus Christ has marked a Christian with the seal of his Spirit by clothing him with power from on high so that he may be his witness.1
1 Cf. Council Of Trent (1547): DS 1609; Lk 24:48-49.