Theravāda Vinayapiṭaka
Nuns’ rules and their analysis
Nuns’ Expiation (Pācittiya) 71
… at Sāvatthī in the Jeta Grove in Anāthapiṇḍika’s monastery. Now at that time nuns ordained a maiden who was under twenty years of age. These were unable to endure cold … Bi-Pc.65. Instead of a girl married for less than full twelve years read a maiden who is under twenty years of age; instead of for full twelve years read twenty years of age. … “… this rule of training:
“Whatever nun should ordain a maiden under twenty years of age, there is an offence of expiation.”
Whatever means: … nun is to be understood in this case.
Under twenty years of age means: not attained to twenty years of age.
Maiden means: she is called a female novice.
Should ordain means: … Bi-Pc.65.2. Read who is under twenty years of age, who has completed twenty years of age. … if she is the first wrong-doer.