IT HAS COME to Miss Manners' attention that there are people who have not mastered the etiquette of breakfast, but who nevertheless think themselves entitled to go right ahead and eat lunches and dinners. First things first, if you please.

Miss Manners is not even talking of such complicated and interesting activities as the hunt breakfast, the wedding breakfast or the all-day Bloody-Mary-and-quiche Sunday breakfast. Plain old, everyday, family breakfast at home, the least structured and most permissive of the day's meals, is being abused daily in breakfast nooks everywhere.

Just because the rules for breakfast are different from those for other meals, that does not mean that anything goes. What a dreadful precedent that would be for getting through the day.

Family breakfast is the only meal for which people can show up as their schedules or inclinations allow, instead of everyone's being expected at the same time. But only the first person down is excused from saying "Good morning" before entering the kitchen or breakfast room. Each new person initiates an exchange of greetings with those already there.

Minnal dress for breakfast is a robe. Miss Manners does not want to hear any coy remarks about the pleasures of appearing in less. Anyone who finds black lace or bare chests appetizing at the breakfast table either has no standards of sensuality or has not concluded the previous evening, in which case taking a break for food, however much daylight there is, cannot be considered legitimate breakfast.

Brushed teeth and brushed hair are also required. Slippers probably should be, also, but Miss Manners is lax about checking under the table.

Breakfast is the only meal at which separate menus may be consumed by different people at the same table. The eccentricities of taste that would be considered finicky at other meals are tolerated at breakfast, where they are believed to be closely related to the emotional stability of the eater. There is nothing wrong with a breakfast table at which one person is having grapefruit, toast and tea; another, orange juice, cereal and milk; a third, cantaloupe, eggs and coffee, and so on.

Provided, of course, it is all properly served. Cereal boxes, milk cartons and other such commercial packaging do not belong on the breakfast table. That rule is absolute. There will be no excuses tolerated about being rushed in the morning. If you must set the alarm ahead in order to have time to pour the cream into a pitcher before placing it on the table, then do so.

At lunch and dinner, the entertainment must consist of conversation. Reading is forbidden when there is more than one person at the table. But at breakfast, one can have conversation, reading or a combination, depending on the tastes of the participants. Miss Manners' preference is to read the paper and periodically announce the news to the other people at the table, but she is aware that there are households in which her life expectancy would not be long.

People may leave the table at different times, but never in silence. Instead of "Excuse me," the customary remark at breakfast is "Oh, gosh, look at the time, I better go now or I'll be late." The correct response to this is "Bye," rather than "Well, then, hurry up -- you remember what happened yesterday."

That is the civilized way to start a day. MISS MANNERS RESPONDS

Q: What is the correct response when another person apologizes to one? I know that the correct response to a compliment is a simple "Thank you!," but that doesn't seem appropriate when someone says "I'm sorry" or "I apologize." Especially if you feel the apology was (a) justified, and (b) necessary. What I want to say is something on the order of "It's about time you realized that you were wrong, you lunkhead!" but I imagine that there are other, more polite, responses which nevertheless convey the opinion that the apology was needed.

A: You are quite correct in imagining that there are more polite responses to an apology than "It's about time, you lunkhead." You are also correct in your faith that there are polite ways of expressing displeasure. Miss Manners, who gets so tried of people blathering about how etiquette is only a matter of making others feel comfortable, is delighted to find someone who understands that etiquette can have other, contradictory, uses.

The response to an apology is always the simple statement, "Oh, that's quite all right." It is the way you say this that conveys your true meaning. Here are a few examples.

1. Acceptance of an apology that was not really necessary. A houseguest apologizes for having gotten his own cup of coffee because he was up early, before anyone else. Host makes a warm smile, usually with head tilted fondly, and puts up both palms in a gesture of bewilderment. "Oh, that's quite all right."

2. Acceptance of an apology for an unfortunate act that was devoid of malicious intent. Guest knocks over coffee cup while helping clear table. Host furls forehead as if troubled at being accused of undue severity and shakes head negatively. "Oh, that's quite all right," he says hurriedly, to close the incident as quickly as possible.

3. Acceptance of an apology for an ill-conceived act that offender immediately acknowledges should never have been committed. Guest spills coffee while using filled coffee cup to represent the ocean in a demonstration of naval tactics. Host pauses before saying anything, looking at offender with a wooden social smile (lips slightly curved upwards, but no trace of pleasantness elsewhere in the face). Then says in an expressionless voice, "Oh. That's... quite... all... right."

4. Acceptance of an apology belatedly offered for a purposely committed major offense, when the offender is not being fully forgiven, but will be allowed to be on probation. Guest makes joke about how bad coffee is, and pours sit in the fish bowl, killing valued fish. Host stares guest down with shocked face (eyes blazing, but mouth carefully closed) and pauses so long that the silence is frightening. Then snaps out, "Oh! That's! Quite! All! Right!" as if saying, "I think that's quite enough out of you."

5. Psuedo-acceptance of an apology for an act for which the offender will never be forgiven. Guest gets into fight with another guest and pours hot coffee over him. Host stands up, posture and face rigid, and waits until he has everyone's attention. Snaps out, in sarcastic tones, "Oh, that's quite all right," as if saying, "I can assure you that nothing you can do, ever again, will be of the slightest interest to me." Host then whips around, turning back on offender, who will soon notice that he is expected to leave the house immediately and forever.

It is Miss Manners' guess that number three is the posture you want. In such a case, a combination of remorse and model behavior should, after a suitable period of probation, result in the offense's being expunged from the record.

In any case, do you see what a complex and entertaining field etiquette can be?