The word χειρόγραφον, more common in Latin than in Greek, is used generally for a bond.  cf. Juv. Sat. xvi. 41, “Debitor aut sumptos pergit non reddere nummos, vana supervacui dicens chirographa ligni.”  On the use of the word, vide Bp. Lightfoot on Col. ii. 14.  The names of the catechumens were registered, and the Renunciation and Profession of Faith (Interrogationes et Responsa; ἐπερωτήσεις καἰ ἀποκρίσεις) may have been signed.