IT IS THE opinion of many people who never attend formal dinner parties that to be obliged to each under such circumstances is a dreadful ordeal. (Many people who do attend such events also consider them an ordeal, but that is a different matter; these people are referring to the conversation.)

Actually the formal dinner is one of the easiest ways there is of taking sustenance. What is impossible to eat, without covering yourself with embarrassment or worse, is junk food.

When a waiter appears at your left with a platter of carefully apportioned food, there is nothing to it. If you don't know what it is, you can ask him; and if you have trouble taking some, he apologizes.

You are provided with a variety of sturdy tools with which to attack the food: large china plates, solid silver knives and forks, a hugh damask napkin to protect you from your own mistakes. Should you select the wrong implement, a whispered word will bring you a replacement. In any case, such errors are less serious than popularly supposed. Most formal dinner tables are not patroled by fork-enforcement officers, and unless you use three implements at a time, it is hard to come out short at the end. The dessert brings its own equipment with it so you'll not be sent to bed without it no matter how badly you muddle the rest of the meal.

Contrast this with the traditional junk food procedure. Looking at your filled plate and asking the person who handed it to you, "What is this supposed to be anyway?" is not advised.

And what a plate it is. Any fool can sit at a mahagony table and eat breast of guinea hen; the challenge is to eat a chili burger from a paper plate while standing up.

If you break your plastic fork while eating in a fast food establishment you may, of course, request another fork. What you cannot do is find all the broken-off tines of the first fork because they have disappeared into the food. bThe refined eater of junk food consumes many silvers of white plastic.

Here is Miss Manners' list of really difficult-to-eat foods -- oysters, artichokes and frogs' legs not being among them. HOT DOGS

While the hot dog in a bun is finger food, this does not include using the finger to push the meat along so that it will come out evenly with the bun at the end. The way to eat a hot dog is to accept the fact that nothing -- not the mustard, nor the relish, nor the meat -- will come out even, so a wad of tasteless bun must be consumed at the end. FRIED CHICKEN

The fingers are of great use here, in prying off the hugh globs of fried fat and placing them quietly on the side of the plate so that the chicken itself may be eaten. PIZZA

This may be lowered into the mouth by hand, small end of the triangle first, taking care that the strings of cheese also arrive in the mouth. SLOPPY JOE The only way to eat this neatly is to eat the paper plate on which it is served; lifting the food out of it is a mistake. CHEESE SNACKS

If a fingerbowl is not served with this, it is best to find a water fountain afterwards for the same purpose. Do not shake hands with anyone directly after eating cheese snacks. FRENCH FRIES

A quick motion of the wrist, such as one uses to shake down a thermometer, will remove excess ketchup. MISS MANNERS RESPONDS

Q. Recently, a very dear friend and I gave a party. Nothing elaborate, just snacks and drinks for some thirsty people. Our problem arose when one of the guests brought a friend. We did not mind the extra person here or there; on the contrary, we enjoy meeting new people. However, this young man decided, once inside the house, that it was a tad too warm, and promptly removed his shirt. Apparently, he thought this gesture reeked (if you'll pardon the expression) of machismo, and was a marvelous way to get the girls to swoon.

Needless to say (but I will say it anyway), he was wrong. The majority of us were, to say the least, fairly repulsed by his actions. As hostess at this gathering, I did not like to see one individual make the others feel so uncomfortable, but I was at quite a loss of what to do.

Finally, I took him aside, gently explained the situation, and as politely as possible, asked him to please put his shirt back on. Was I wrong in doing this? It is obviously too late now to correct myself; however, if ever faced with something like this again, what would you recommend?

A. You are right to feel an obligation, as hostess, to see to the comfort of your guests. Explaining that you were having a formal evening, that clothes were being worn, was perfectly acceptable. If you wished to make the offender particularly comfortable, too, in any temperature, you might have hinted that the ladies found his dishabille "disturbing."

Q. Will you please advise as to whether there are any rules or traditions as to wearing a wedding band after the death of a spouse.

A. The ring is worn as long as the survivor feels like remaining a part of the marriage, and taken off if that person becomes again susceptible to romance. Unfortunately, there is no way of symbolizing the natural desire to want to do both.

Q. I don't even know if you will print my kind of complaint, but I hope a lot of readers will notice it and do something about it.

I cannot understand why the hairstylists of this world won't do anything about this long, sloppy hair on girls and are letting it go on forever. We always have to see them brushing their hair away from their faces and having to eat with them in diners, etc., it's a sickening sight.

A. It will take Miss Manners a moment to collect herself before answering you. She is shocked and upset and even has a tear or two to brush away from her face before she can trust herself to think.

You see, Miss Manners has very long hair herself. She doesn't wear it down at her age, but she always thought it proper for young girls to do so, and never worried that hair stylists or other free-lance critics, such as yourself, were policing the streets, looking for visual offenders.

But if you must, please try to remember -- it's the girls who bob their hair who are fast.

Q. At the family table, where meals are usually served as one course and on one plate, which of the following approaches to eating a meal is considered more proper: (1) Partaking alternately of the different items at one's place, or (2) consuming each item in itsentirety before proceeding to the next? Or are both ways equally correct?

A. Miss Manners is tempted to turn tolerant now and say, "Oh, go ahead. Eat in the order you like. What does it matter?" But then she began to consider that you probably have children, and that their future must be considered. So here is a more responsible answer:

In the American style of eating, fork in the right hand, it is improper to have more than one food to a mouthful. Surely you will grant that. Technically, then, there is nothing wrong with taking, say, a forkful of steak, sequestering it in the cheek, and then sending along a forkful of mashed potatoes to accompany it. Provided, of course, that you do not open your mouth while it contains foods. (In manners as in less worthy causes, cheating and discretion must be inseparable.)

There are variations on the principle of alternation, which is the conventional method and the one Miss Manners recommends you train your children to prefer, even if it is too late for the adults.

Why? Because the variations possible on the principle of eating all of one food and then going on to another are even more fraught with danger, if you can imagine that.

Do you eat the food you like best first and the one you dislike most last? Or do you start with the chore and save the treat?

Both methods are practiced, but children always chose the first, becuase they have no real sense of the future. If you allow them to do so, your life will be filled with conversations that go:

"Eat your eggplant, dear."

"I can't, I'm all full."

Is that the memory you wish them to take through life of the beloved ritual of family dinner?