Whenever I write, I try my best to be correct in matters of spelling, grammar and usage. In other words, I'm careful to "mind my p's and q's," as people sometimes say.

Appropriately enough, The Associated Press Stylebook, which I often consult, quotes that very phrase in the entry under "apostrophies." It does so to demonstrate the right way to form plurals of a single letter.(The stylebook also uses "The Oakland A's won the pennant" as an example, but that's another story.)

Back to p's and q's. The odd phraseology makes you wonder what the letters originally stood for. Did they have a specific literal meaning before acquiring the current proverbial sense of doing the right thing?

There's no shortage of explanations for "Mind your p's and q's," all of them absolutely unproven, and many of them contradictory. Legends, rather than linguistic evidence, tell us what the phrase supposedly meant.

The most common explanation for "p's and q's" assumes that the letters refer to the type used in printing. A recent letter from a former type-setter to a popular advice columnist made this claim:

"The expression harks back to the days when type was set by hand, letter by letter. Of course, the letter on each piece of type looked `backward' in order to print `forward'; hence it was very easy to mix up lowercase p's and q's, and apprentices were constantly admonished to `mind your p's and q's.' "

That story sounds reasonable since q follows p in the alphabet. On the other hand, b's and d's or even u's and v's might also be hard to distinguish.

Although typesetters may use the expression, there's no absolute proof that it originated in this trade.

No problem, since other people say "p's and q's" really refers to handwriting difficulties. Supposedly the saying was started by teachers instructing children who were learning to write.

I guess only two letters of the alphabet were hard to distinguish, since I've never heard anything said about students having to "mind" other troublesome pairs.

But the folklore of "p's and q's" doesn't stop there, not by a long shot (who knows where that saying came from).

Another popular story is that English pub keepers marked p (for pints) and q (for quarts) on a slate when serving drinks on credit to regular customers. The saying "Mind your p's and q's" was an admonition to pay up because the bar tab had become too large.

That story sounds plausible, too; but it's a difficult one to reconcile with another explanation that claims early American colonists originated the expression to warn against confusing the religious beliefs of Puritans and Quakers.

Several of my students have said that high-school history teachers told them that this was the saying's actual origin, although the teachers never provided any proof beyond looking wise as they told the tale.

An exotic explanation of "p's and q's" is that the saying came from French dancing masters who repeated it in order to caution their pupils always to monitor the correct positions of feet and pigtails (pieds and queues in French).

This improbable story was topped by one in Bergen Evans' Dictionary of Quotations. Evans ignored the typesetting and handwriting theories, and only mentioned the stories about pub keepers and French dancing masters. Instead, he suggested the following as a likely explanation:

"Some say it's advice from sailors' wives to their husbands to be careful not to get the tar from their queues (pigtails) onto their peajackets."

Evans doesn't identify who says this, so I suspect that he simply heard it somewhere, liked it and published it.

Frankly, I think a better saying for sailors' wives to use in that situation would be "Don't get any q.t. (queue tar) on your pj's!"

If you ever hear that version quoted, you can safely say that you know its origin. I just made it up.

"Curses! Broiled Again," Jan Harold Brunvand's fourth collection of urban legends, is now available from Norton. Send your questions and urban legends to Prof. Brunvand in care of this newspaper.