Odd times beget odd books and it is odd times when a 35-year-old man can write an article in this newspaper explaining that he recently attended his first wedding ever. Not because he was such a lump he was on everyone's don't-invite list, but because never before, in all his 35 years, had he had a friend get married.

Live together, of course. And have relationships, man to woman, man to man, woman to woman, everyone to everyone else in the commune, est group or revolutionary cadre. But now it seems that all this freedom, this Whitman Sampler of sex, has begotten its own problems and produced a new generation that yearns for certainty.

In great-grandmother's day, everyone knew exactly what presents a woman could accept from a man without being thought fast, and right up to the 1950s, both men and women were secure in the knowledge that commitment was a progression from letter sweater to class ring to fraternity pin to engagement ring and finally to marriage. Both men and women knew at which point a hand could begin to dally below the neck, when, with minor argument, it would be allowed to move down past the waist, and exactly what degree of commitment was called for before a man was allowed to unhook a bra.

It was this stifling predictability--the feeling that such sexual trade-offs were hypocritical--that led people to push for the freedom to experiment. Back then, everyone was kicking over the same traces, and if no one knew exactly where they were going, it was enough to know where we'd been.

But, alas, the job of blowing up the past is easier (and more fun) than that of building the future. Cheryl Merser has allotted herself the unenviable chore of writing the first book of sexual etiquette for the generation come to fruition in the '80s. She tackles such contemporary questions as: Is it rude to ask someone you have just met (but are preparing to climb into bed with) whether he or she has herpes? Answer: No, though Merser concedes there is no graceful way to put the query.

The etiquette writers of old knew exactly when to order you to put on your gloves or take off your hat. But Merser, like the confused generation she is writing for, lacks that certainty and constantly remands us to the kindness of our peers. She reminds us, and it is unfortunate that it is probably necessary, that lovers ought to be at least as kind to each as they are to strangers.

True, but nowhere near as definite as Emily Post would have been if, God forbid, she had ever had to arbitrate sexual encounters: "A lady does not make the bed unless it is in her own house"; "For every three evenings the two of you spend in your bed, consideration dictates that for his convenience you must offer to spend one in his," etc.

Reading Merser on the problems of a modern sex life goes some way to explaining the new celibacy. His ex, or not-so-ex, lover, her venereal disease, his children, her career, his/her doorman, his separate vacation, her house in the country. How we do go on!

Merser sympathizes with the victims, caught in a time when the roles of men and women are being redefined, and her advice is always kind, though sometimes silly, as when she suggests you might indicate a growing commitment by offering to give up a part of your dresser to your lover, "who then has a drawer, a stake in your life." I guess, though most of the men I've known would have wondered why they were being asked to relinquish their very own chair back or corner of the floor.

A word about the book's style: It is much too cute, running rampant through a group of people who enter with such sober monikers as Thomas or Margaret only to reveal themselves as Morticia, Drudgina, Seaworthy and Timidia.

The problem of making up names is that not only do the cases seem to be invented, but carelessness (or is it a sign of the mixed-up '80s?) can cause Carey, who starts out in bed with Tony at the top of Page 130, to discover, mid-page, that it isn't Tony at all! It's Nelson.

Ultimately, as many a philosopher has pointed out, growing up is learning to live with uncertainty, but if you want a book that will reassure you that a lot of your contemporaries are floundering around in the sexual sea, this is the one. For rules, you must return to Emily Post.