Assuming that practically nothing comes naturally, Miss Manners will now explain to girls and boys how to be girls and boys during their school prom festivities. After that, they are on their own. Miss Manners goes to bed early.

Who is the boy and who is the girl has nothing to do with who is the host or hostess. That was presumably settled long before prom time.

The current confusion seems to have to do with changing patterns within the adult world based on increased financial independence among ladies and a resulting increase in frankness about their providing and reciprocationg hospitality. Very young ladies are not the only ones to combine the new with the old tradition in the worst possible way by issuing invitations to gentlemen and then presenting them with the bills.

Miss Manners does not suspect teen-age girls of trickery when they invite boys to their dances and then inform them, in advance or on the spot -- not a good idea when you are dealing with gentlemen too young to carry credit cards -- that they are responsible for related dinners and incidental expenses.

Rather, she thinks that when they do the inviting, the girls are in their jeans and their fathers' shirts and think of themselves as using the same behavior patterns as boys. But when they get into the prom dresses that Miss Manners is so pleased to see come back into fashion, they switch to the pattern of being a girl that they believe to have been in use the last time such dresses were worn.

Since that may have been MANNER AD 1,COPY,SY,ACT,COPY,,,slightly before their mothers' day, they are not getting accurate guidance. They imagine that a girl who who wore pretty dresses never lifted a finger, certainly not to put it into her own wallet.

Not exactly. Even under the system whereby the boy did all the inviting and the girl did all the waiting for the telephone to ring. some attempts were made at reciprocation -- a home-cooked meal, a present of hand-knitted socks or scarf, a story about having been given theater tickets by a convenient aunt.

That things still did not come out even financially, Miss Manners is quite aware. There used to be a nasty expectation on the part of nongentlemen about the returns they calculated on their investment od different amounts -- so much for a movie and sodas, so much for a real restaurant dinner and so on.

In the hope that we will never hear that sort of vulgarity again, we now have the Dutch treat for informal occasions among the young and, for adults, the more open practice of taking turns being hosts.

But paying the ills for an evening's entertainment does not make a girl into a boy. Therefore, she does not have to mimic the boy pattern by calling for her date, for example; nor does she have to start making him pay the bills in order to retain the role of girl.

Paying the bills simply makes her the hostess.

The hostess for a prom night makes the arrangements for the evening and pays for dance tickets, meals and any extras she may wish. She neither assumes herself nor demands from her escort such male functions as sending flowers, opening doors or leading on the dance floor.

(These are merely little superficial social customs, graced by tradition and pleasant to practice. They go with your pretty dress, which also, you may notice, bears a significant gender distinction from your young man's formal clothing.

(Such differences are not to be over analyzed for sociological content. Equality in essentials does not require total sameness in everything.

(There is nothing whatever contradictory about allowing a gentleman to hand you out of a car and the smashing him one on the volleyball field or the debating society.)

The rewards of being a hostess are the same as those of being a host. You get to choose whom you want to invite, you get to submerge your feelings of outraged disappointment when politely turned down and you get the satisfaction of having devised an evening of entertainment that provides as much pleasure to yourself as to your guest.