DEAR MISS MANNERS: The traditional checkout process at stores and fast-food restaurants has always been a separate line for each cash register, and if you happened to end up in a slow line, that's just the way it was.

However, some places, like banks, have switched to a single "wait here for next available cashier" model. Studies have shown this is generally faster and more efficient, but when there is nothing to indicate one way or the other, what is the prevailing etiquette? Is it one line or multiple lines? Should people be allowed to straddle multiple lines?

I shop at a local pharmacy store that has two cash registers at the front, one across from the other, with a single aisle between them. Every time I have shopped here in the past, there have been two separate lines, with people standing on the left side of the aisle to wait in line for the left cashier, or the right side to wait for the cashier on the right. Today there was a college-aged man standing right in the middle of the aisle, so I politely asked him which line he was in. His reply was "The ONE line," with a tone that implied I was an idiot for asking.

There is no sign indicating "wait here for next available cashier," so is it wrong of me to assume that there were actually two separate lines, and he was wrong for trying to straddle both lines?

GENTLE READER: Designing checkout lines -- like manning cash registers and stocking shelves -- is a store responsibility. Smart managers are aware that fistfights among the clientele are likely to interfere with business, and therefore try to make such layouts unambiguous.

When ambiguity does exist, Miss Manners allows free rein to the (reasonable and well-intentioned) whims of the first person in line: Everyone behind will then have to conform, at least until a lull in business anoints a new trailblazer.

If the aisle between the two cash registers has a function -- the only way out of the store, for example -- then your college-aged man failed the tests of reasonableness and good intentions. But you would be prudent to wait until someone plows into him on the way out, and, while expressing concern over his misfortune, advance to the closer register.

DEAR MISS MANNERS: Two couples were dining at a fairly expensive restaurant. Just as the main course was being served, one of the men seemed to pass out in his chair, his head resting on his chest.

His wife couldn't rouse him, and she asked that someone call 911. EMTs came, revived him and said they would take him to the hospital.

The server asked if she could box up the uneaten entrees. The diners declined, saying that they were all going to the hospital. The server then asked what she should do with the dinner bill.

One of the diners paid it. My friend, who was at the next table, felt that the restaurant should have comped the meal. I disagreed.

GENTLE READER: Unfortunate though the circumstances were, the restaurant is under no obligation to refund the price of the meal. Assuming, Miss Manners hastens to add, that it had no hand in causing those circumstances.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: In college, I lived in a townhouse with several housemates. One night, when a party we were hosting had gone on too long for my taste, I went down to the basement and turned off all the circuit breakers.

It had its intended effect; the house was cleared of guests within minutes. A few minutes after that, one of my housemates came down to the basement to see what happened. He was very amused when he shined his flashlight on my grinning face, standing next to the circuit breakers.

GENTLE READER: Please stop grinning. Yes, you got away with it. But Miss Manners begs you to stop thinking of this as cute before you turn off someone's life-saving medical device.

DEAR MISS MANNERS: When salad is eaten after the main course, should the salad fork go outside or inside the table fork? I have often seen the salad served after a main course, before dessert, but I have never seen the fork moved. Assuming the salad is presented after the main (meat) course, what is the proper setting?

GENTLE READER: Maybe your hosts are just used to seeing tables set that way because restaurants can produce salad before the main course (to placate clients while their main courses are being cooked). The reverse sequence is proper for a private event, where dinner is already in the works.

But maybe your hosts are just trying to drive you crazy. People love to ridicule etiquette for the supposedly Heraclean problem of choosing which fork to use, when the answer couldn't be more simple: Start at the outside and work your way in. So the salad fork goes inside when it is to be used after the meat course.

Miss Manners cannot decide which would be more delicate -- to use the salad fork for the salad, despite its misplacement, or to use the dinner fork for salad and the salad fork for the main course to avoid pointing out that your host doesn't know how to set the table.

DEAR MISS MANNERS: I used to be comfortable about responding to invitations and announcements, but some recent ones from longtime friends have left me wondering:

"We would like to invite you to a wedding concert with some informal dancing (date, time, location). NO PRESENTS, but please bring a potluck finger food that does not need refrigeration plus a bottle of champagne to share. Please do not tell others and RSVP ASAP so we can fill your spot if you cannot come." No mention of any wedding for this decades-long co-habiting couple.

"Please join us at our son Englebert's graduation ceremony (date, time, location). Although he will not be able to attend, we look forward to sharing this event with you."

"Penelope died yesterday -- no services, and PLEASE, no flowers or condolences."

"A baby shower for Lulu and Axelrod (people we have never heard of) is being given by their friends (who are not identified by names or any return address). No need to attend -- just mail a gift card to the home of her parents (whose identities are also unknown to us)."

"We've moved! Housewarming gifts may be sent to (new address). We look forward to seeing you sometime in the next year or so!"

How should I respond to each of these?

GENTLE READER: Why would you want to?

If you share Miss Manners' belief that not answering invitations is a high crime, she thanks you. But these are not exactly invitations. The wedding concert is a suggestion that you prepare yourself a picnic. The graduation is a ceremony that even the guest of honor has declined. The death announcement has allowed no opportunity to mourn. The shower and housewarming request contributions without attendance.

If you actually know these people, it would be kind to send congratulations or condolences, despite their not having expressed warmth or offered hospitality.

DEAR MISS MANNERS: It has always been my understanding that it is common courtesy and common knowledge that one should keep to the right when walking along sidewalks, stairwells, hallways and other public walkways. However, over the past several years, I've increasingly noticed that many people seem to walk to their left and even refuse to yield when other pedestrians are coming toward them from the opposite direction.

Were the rules changed without my knowledge?

GENTLE READER: Are you asking Miss Manners whether the Etiquette Council met, when everyone was marching smartly to the right, and ordered them all to the left (except for those who got special permission to meander)? Or whether there was a hostile takeover from the British branch?

No. You are just running into people who don't follow the rules. Or they are running into you.

DEAR MISS MANNERS: Is it still correct to congratulate only the groom and give the bride best wishes, or has that rule changed?

GENTLE READER: That one hasn't changed, either, but nobody knows it and violating it does no harm.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)