Admission to candidacy for ordination as deacon comes about by means of a special liturgical rite, “by which one who aspires to the diaconate publicly manifests his will to offer himself to God and the Church, so that he may exercise sacred orders. The Church, accepting this offering, chooses and calls him to prepare himself to receive a sacred order, and in this way he is rightly numbered among candidates for the diaconate.” (Basic Norms for the Formation of Permanent Deacons)
Enrollment among the candidates for the diaconate does not constitute any right necessarily to receive diaconal ordination. It is the first official recognition of the positive signs of the vocation which must be confirmed in the subsequent years of formation.