Nuns’ rules and their analysis
Nuns’ Expiation (Pācittiya) 86
… at Sāvatthī in the Jeta Grove in Anāthapiṇḍika’s monastery. Now at that time a certain nun frequented a certain woman’s family. Then that woman spoke thus to that nun: “Please, lady, give this petticoat to such and such a woman.” Then that nun, thinking: “If I go away taking it in my bowl, there will be trouble for me,” went away having tied it on. When she was on the high road the strings broke and were scattered. People … spread it about, saying: “How can these nuns wear a petticoat, like women householders who enjoy pleasures of the senses?” Nuns … heard these people who … spread it about. Those who were modest nuns … spread it about, saying: “How can this nun wear a petticoat?” …
“Is it true, as is said, monks, that a nun wore a petticoat?”
“It is true, lord.”
The enlightened one, the lord, rebuked them, saying:
“How, monks, can a nun wear a petticoat? It is not, monks, for pleasing those who are not (yet) pleased … this rule of training:
“Whatever nun should wear a petticoat, there is an offence of expiation.”
Petticoat means: whatever goes about the hips.
Should wear means: if she wears it even once, there is an offence of expiation.