Words like CD and 1960 have plurals of CDs and 1960s, although CD's and 1960's were once the recommended way of doing it.
If making a plural with just an s might be confusing (as with single lowercase letters), you can use an apostrophe. So dot your i's and cross your t's. But give people credit: mostly they know a plural when they see one -- there's no need for apostrophes in:
They sent out three SOSs. We have videos for sale. She got five As in her exams. A list of DOs and DON'Ts.
Perhaps the first apostrophe in lower case do's and don'ts is wise.
I've quoted this in other places. It's still standard to mark the plurals of abbreviations and years with the apostrophe.
From The Oxford Companion to the English Language:
There was formerly a respectable tradition (17-19c) of using the apostrophe for noun plurals, especially in loanwords ending in a vowel (as in We do confess Errata's, Leonard Lichfield, 1641, and Comma's are used, Philip Luckcombe, 1771) and in the consonants s, z, ch, sh, (as in waltz's and cotillions, Washington Irving, 1804). Although this practice is rare in 20c standard usage, the apostrophe of plurality continues in at least five areas: (1) with abbreviations such as V.I.P.'s or VIP's, although such forms as VIPs are now widespread. (2) With letters of the alphabet, as in His i's are just like his a's and Dot your i's and cross your t's. In the phrase do's and don'ts, the apostrophe of plurality occurs in the first word but not the second, which has the apostrophe of omission: by and large, the use of two apostrophes close together (as in don't's) is avoided. (3) In decade dates, such as the 1980's, although such apostrophe-free forms as the 1980s are widespread, as are such truncations as the '80s, the form the '80's being unlikely. (4) In family names, especially if they end in -s, as in keeping up with the Jones's, as opposed to the Joneses, a form that is also common. (5) in the non-standard ('illiterate') use often called in BrE the greengrocer's apostrophe, as in apple's 55p per lb and We sell the original shepherds pie's (notice in a shop window, Canterbury, England).
Thanks goofy. Do you have an origination date for that?
The OCEL notes usage variety and doesn't usually care to make recommendations; naturally enough, as it is a companion, not a guide. It says the apostrophe of plurality "continues" in the given cases (with which I agree), but it does not say -- as you suggest -- that it is "standard". Indeed, it notes the last one is "non-standard". I'd say that (4) is tending that way as well, although it is undoubtedly widespread. The others are common, but possibly not to be preferred? Here we are allowed to be a little more prescriptive, possibly.
It's an interesting contribution, goofy, well worth pointing out. But you'll be aware that some books aim to be descriptive, some prescriptive (and some are a bit of both).
The OCEL is (in my view) very very descriptive. That's not a criticism -- quite the opposite -- but it does mean that it tends to record usage without comment. You can see that in
... the use of two apostrophes close together (as in don't's) is avoided. (3) In decade dates, such as the 1980's, although such apostrophe-free forms as the 1980s are widespread, as are such truncations as the '80s, the form the '80's being unlikely.
Use of is avoided rather than is best avoided or should be avoided is very descriptive: it's saying what is, rather than what's right, and it's not helpful when trying to decide what most people would regard as "standard". All we know is that it's what some people say.
The whole area is a minefield (who decides what's right? Who sets the standard?) so I don't blame the OCEL at all. But you can't claim that finding something in the OCEL makes it standard.
Perhaps the preface to the OCEL can clarify? Sadly I have lent my copy, so cannot check.
The Preface doesn't have much to say. The entry on "standard English" doesn't either; it gives a lot of definitions of what standard English might be.
The full entry on the apostrophe of plurality is here. ymmv but it suggests to me that the first four usages are standard and the fifth one is not: "Although this practice is rare in 20c standard usage, the apostrophe of plurality continues in at least five areas"
The full entry on the apostrophe of plurality is here. ymmv but it suggests to me that the first four usages are standard and the fifth one is not:
Well, my m does v, I'm afraid. That seems to me like a model of a standard descriptive (not prescriptive) piece. It studiously avoids trying to classify or label anything (for example as standard or non-standard) except in the most uncontroversial areas; my memory of the book is that it includes articles on (for example) Black English and Yorkshire English, so I don't think you can assume that it refers to Standard English by default. No, it seems to me to simply record usage (and quote other authors) without comment or condemnation, which is as it should be. Sentences like "There is also widespread difficulty with its and it's" lead me to think it's talking about English as it is used, rather than standard English per se.
The use of -'s to form the plurals of numerals, abbreviations and symbols is not now as common as pluralization with simple -s; 1970s, CPUs, &s are more likely to be found than their apostrophized counterparts. A dissent can be found in Safire 1980; he prefers 1980's, and the 80's to the '80s.