No need to sit up when you eat out, New York restaurants are declaring. Several are promoting a new custom of serving meals in their lounges, where, instead of being seated at dining tables, customers can sit or sprawl in easy chairs or sofas, and eat with their plates on their laps or on knee-height coffee tables.

No need to dress up, proclaims an opera company in its new brochure titled "No Dress Code." After announcing that excitement will begin to fill the theater when the lights dim, it repeats: "And there's no dress code. Come in formal wear, come in jeans. It doesn't matter. The important thing is not to miss our sizzling season."

Miss Manners is familiar with the kind of meeting from which such ideas spring. The topic of the day is "How are we going to attract more young people?" and it gets off to a jolly start with the announcement of how soon the participants can expect all of their present subscribers to be dead.

There follows an unproductive but humorous exchange of remarks characterizing the clientele as already in a state of mental and stylistic deterioration. Never mind that the people who engage in this banter are more or less the same age, and that the token young person present is wisely limiting his or her participation to discreet eye-rolling.

To get things back on track, the leader produces figures representing the buying power of young people. There follows an unproductive but enthusiastic exchange of remarks characterizing the young as useless and spoiled. It concludes with all the participants agreeing that this is the clientele they want.

They are then asked to figure out how to attract them--not unreasonably, as this is the point of the meeting. This leads to a pooling of information about the ways the young differ from the moribund people the organization has successfully attracted. After a number of participants have unloaded specific grievances about their own children, everyone agrees on a few general characteristics of people under 30:

They can't sit up, and they can't dress themselves. They have no attention span. They recognize trends, not quality. They will spend any amount of money if they think it gains them status. They will not put up with any discomfort for any reason. They have no experience of the traditional refined pleasures and are intimidated by them.

Now those attending the meeting feel they are getting somewhere. They start turning this material into policies that would make the young comfortable and allay their fears while attracting their money. Making their enterprises "approachable" turns out to mean making them as much as possible like the experiences the young already have.

If younger people customarily eat lounging in front of a television set, restaurants should not require them to sit straight. If they are in the habit of listening to music in lounging clothes, they should be encouraged to do so in opera houses.

Why any young person made aware of these assumptions doesn't stalk off in a huff, Miss Manners doesn't understand. Low attention span and unwillingness to learn would be the explanation offered by those with designs on their money.

In fact, the young are no different from the old in wanting informal dining and entertainment on many, perhaps most, occasions. But they are also like everyone else in wanting excitement and variety. That they yearn for occasional formality is only too obvious on prom night and at their weddings; that they like venturing where they have to try hard to pass muster is obvious in the lines hoping to get into popular nightclubs.

By dumbing themselves down "so as not to seem stuffy," as they say, businesses associated with grown-up glamour don't look youthful; they just look less glamorous. Stuffy--if they only understood--is what they have going for them.

Dear Miss Manners:

Please come to my aid by placing on the rudeness scale the following:

1. Inviting people to your home and ambushing them with wedding or vacation videos.

2. Inviting people to dinner and serving them food prepared without fat or oils because you prefer it, when you know your guests will not.

Sorry as she is that you had a dull time, Miss Manners has to tell you that she doubts that your fatless-but-fatuous friends made a serious dent in the rudeness scale. True, they should have warned you about the videos and might have slipped something fatty onto your plate unless they never have it in the house.

But motivation also counts. Unless they planned to amuse themselves by insulting your palate and boring you senseless, they are only misguided hosts, not seriously rude ones.

(c) 1999, Judith Martin