There are two distinct types of people on the party circuit, whose customs and ideas are so much at variance that misunderstandings are inevitable and bitter clasjes frequent. One group is called Hosts, and the other, Guests.

Miss Manners often wonders, considering how little these groups have in common, why they socialize at all. Hosts are by far the more fastidious lot, and she is sure that if they knew anyone else to invite to their parties besides Guests, they would never let those thoughtless people into the house.

For example, Guests firmly believe that the rule about having to let Hosts know whether you are accepting their invitations has been repealed. "Nowadays" -- a favorite term used to designate a generally lawless state -- they explain, "no one expects anyone to answer invitations."

Except Hosts, of course. Hosts have never for a moment wavered from the absolute rule that all invitations require quick responses, and can cite impressive reasons: They need to know how much food to cook, how many places to set, what sort of a group they will have and therefore who would go well with it and so on.

Guests believe that the bigger the See MANNERS, H17, Col. 1 function, the less it matters whether they signify a desire to attend. And Hosts are sufficiently intimidated that they prefer to pretend that it is not they who are so petty as to care to know who is coming to their weddings, but some perfect stranger, such as the caterer.

Guests are confident that they are warmly welcome if they show up at something that they did not accept, but also that Hosts will not notice if they fail to show up at all.

However, Hosts always notice who has attended their functions, no matter how large. Even those who are sincerely overcome with bereavement notice who has attended a funeral and who has not. And even though Guests feel free to enter parties without greeting those Hosts, or depart without saying goodbye, Hosts always notice who has been there, when they left and what duties they skipped.

Paradoxically, the same Guests who believe that Hosts don't notice or care if they attend believe that Hosts are always radiant with pleasure at the additional opportunity for hospitality provided when strangers show up on their doorsteps. Guests therefore feel free to invite their own Guests, all of whom have been assured that Hosts are infinitely flexible about the number of Guests they can accommodate.

This faith in Hosts' lack of concern with numbers extends to the matter of timing. Guests never believe that Hosts are serious about the hours they put on invitations, but will be equally happy to see them whenever they find it convenient to show up, and devastated at their departure no matter how late it may occur.

But in fact, Hosts have a deep preoccupation with timing, and keep pushing dinner back until such time as they think all stragglers will be in. Guests who have obeyed the instructions about time therefore become disillusioned, not to mention hungry and tipsy, while waiting for other Guests and resolve in the future not to repeat their mistake.

On the matter of food, Guests figure that the only interest of Hosts is to please each individual palate, and that therefore it is helpful if they make known their particular tastes and habits. Guests who do this ahead of the party, as they call airlines to order special meals, feel especially virtuous, but those who announce their allergies and other preferences just as dinner is being served also feel within their rights.

Hosts have an unseemly preoccupation with gathering compliments for their offerings, but are not as delighted as they claim to get up from the, including three chocolates and southern pecan. Prints of a Fellow --- table to forage in refrigerators from which the extraneous food was removed to make way for the party menu.

Guests believe that the only serious dress requirement of Hosts is comfort, and Hosts now generally pretend this is true and instruct their guests to wear "whatever you want -- just be comfortable" when they are secretly planning to dress up.

Nevertheless, Guests turn out to feel uncomfortable when they are comfortably dressed, and everyone else isn't.

These rifts are so serious that even Miss Manners is in despair of persuading such different people to adopt a common code of behavior that will satisfy them both. Perhaps the only solution is for Hosts to entertain only other Hosts, and for Guests to confine their visiting to the homes of other Guests.

Q If a respectable woman meets a respectable man in a respectable manner (a book in itself), and the two find toward the end of an evening that their romantic interests have been stirred and they succumb to these interests, what is the proper behavior that should follow, i.e., the next day or the next week?

I've recently found that an annoying habit of some male members of society is to do nothing at all! Of course, such an encounter is not cause for a formal engagement, but it does merit some reaction.

I liken it to the dreadful rudeness of a dinner guest who neither calls nor writes to tell the hostess her company was enjoyed.

A You wouldn't care to lend Miss Manners the "book in itself," would you? There is nothing like a nice story about passion run amok to while away a winter's afternoon.

As a rule of living, however, it has its disadvantages. The trouble with strangers is that one doesn't know anything about them.

It is not just that one doesn't know if their manners include thank-you calls, but one doesn't even know their definitions of what should make them grateful.

You have charmingly described such encounters as succumbing -- presumably to rare and uncontrollable passions. It is perfectly possible, however, that to the strange gentlemen, these are routine incidents, devoid of romance, in the category that Miss Manners believes is known as the one-night stand. The one-night stand is characterized by the time limit stated, and by its lack of obligations.

That is why respectability has that tedious requirement of checking out emotions and manners before intimacy.

Q I have recently had the good fortune to be dating several gentlemen simultaneously, two of whom are friends. Miss Manners will certainly recall the problems this otherwise pleasant glut can entail, if she is not currently having them herself.

Can you suggest a gracious way of informing Mr. B. that Friday is taken, without resorting to the overused "busy" (femalese for "not interested")? What can be done to prevent Mr. A., Mr. B. and Mr. C. from running into each other "coincidentally" while making informal visits to my residence, and what can be done to make each comfortable when it does happen?

My mother, who is a strong believer in the male competitive drive, thinks these situations are to my advantage. But so far I feel inept at the jungle etiquette, having been on the other side before, and not feeling the least urge to compete.

A Competition is such a strong term. So is jungle etiquette, for that matter.

Let us just say -- your mother and Miss Manners -- that a gentleman is supposed to have to make an important effort if he wishes to secure exclusive rights to a lady's company. Otherwise, he is going to experience a little discomfort in finding that she is not always available to be with him, and even in discovering that she has other gentlemen friends.

This is not a disgrace, and should not be so treated. One way to prevent them from running into one another is to let it be known that you do not entertain unannounced visitors. "Do call if you're thinking of coming over -- I'd like it to be at a time I can receive you properly" is femalese for "I don't really plan to account to you for my time."

You are right about too much busyness meaning "Go away," but "Oh, I'm devastated that I'm not free then -- some other time, I hope," means "Keep trying."

Q I would like your opinion on couples who have lived together openly -- sometimes for several years -- who decide to get married. Suddenly, the woman acts like the virgin who needs china, silver and other gifts.

During a recent situation of this nature, the groom's mother made it obvious to friends that she expected them to entertain this couple with many large parties, some showers and at a big church wedding. The "bride" wore a long, white formal gown and long white veil. What a farce!

Wouldn't a small family wedding be in better taste? If a couple chooses to break with tradition, that is their business, but to expect people to treat them as a traditional bride and groom is greedy and distasteful. What do they do new on their honeymoon?

A Miss Manners was not aware that only virgins needed china and silver. Nor is she in the habit of speculating about what couples do on a honeymoon, but she dares say that all of them think of something.

To her mind, a bride is a bride, and a wedding is a wedding, regardless of what form the courtship took. Young first-time brides generally do wear white dresses, but as these are not transparent, the wedding guests are not supposed to concern themselves with the state of the goods inside.

It is always improper for the bridegroom's mother to announce obligations to others, and that should therefore be steadfastly ignored. But people who disapprove of a bridal couple, for whatever reason, need only decline the wedding invitation.