Article 99 — — (2) Explanation.

1) It is necessary and sufficient in order to have an irregular union that the behaviour of the man and of the woman be analogous to that of married people. 2) They need not represent themselves to third parties as being married. 3) The mere tact that a man and a woman keep up sexual relations between them, even if repeatedly and notoriously, is not sufficient by itself to constitute an irregular union between such man and woman.