Are you supposed to put an apostrophe + "s" when using multiples of an acronym?

Geo, it's almost always used. Don't know why, it's a mystery to me too

So there's no known formal grammar rule for this?

Or, is it formal / proper to use the apostrophe + "s", but there's no clear explanation or logical reason why (besides perhaps out of convention based on people's habit of using it over time)?

Or, is it grammatically improper to use the apostrophe + "s", but people do it anyway, perhaps because it's grammatically such a minor point that it's both overlooked and ignored?

If it's the former two, I'll keep using the apostrophe + "s" (I believe that you're referring to one of these two cases). If it's the latter, then I'll keep the apostrophe out in the future.

I used to insist on doing it like this: NGOs. However, not too long ago I read where the apostrophe is actually preferred by many/most professional writers and stylists: NGO's.

http://public.wsu.edu/~brians/errors/acronyms.html

That's not to say that the issue isn't debated, though:


http://english.stackexchange.com/questions/55970/plurals-of-acronyms-letters-numbers-use-an-apostrophe-or-not

http://english.stackexchange.com/questions/503/what-is-the-correct-way-to-pluralize-an-acronym

If it is presented as Ngo, I think the apostrophe is essential to keep Ngo from being confused with some other abbreviation. Ngos could be something entirely different. If NGO is in all caps, NGOs is entirely clear.

I'm sure that my own inconsistency wouldn't make a good rule.

Yup. When I'm doing academic writing, I have to abide by the MLA guidelines. They say, in so many words, in cases like this rules be damned, do whatever makes your meaning clearest. Successful communication is the ultimate goal, not rule-following.

I learned an important lesson when I worked for Florsheim in management. My boss told me to write administrative letters to managers to the dumbest one. My secretary was very helpful in accomplishing that feat.

Good advice there.

About that secretary: she saw the potential of having an accounting degree, so she began her studies not long after that. Her name was Barbara, but I didn't hear back from her before I left Illinois to return to California.

That is, to me, unfathomable. I took exactly one Accounting class in university. Hated every aspect of the classwork. Dropped the class even though the prof was a knock-out redhead, so that tells you how much I hated it.

I ran into accounting by a fluke, because all business majors had to take accounting 101, and I got an A. The rest, as they say, is history. LOL Made a pretty good living off of it too!

Accountants do bring home some pretty decent bacon, don't they? Maybe if I'd known that at the time, I might have changed my mind about it.

Personally, I don't think it's ever correct to use apostrophes to indicate plurals.

Will FBM's assertion apply to all the FBMs in the world?
Pretty clear to me.

Indeed!

Absolutely. Thank you. At last. Photo's, taxi's, 1's and 2's, NGO's, IED's - all wrong.

As a former tech writer, we used to talk about things that made our hair strand on ends. it's this use:

Prime example was the persistent spelling of CD's. and the same for PC's.

Why put an apostrophe there as the plural of the word? Made no sense.

My guess is that CD and PC are initialisms, and some people seem to think they need an apostrophe before the plural s. They don't.

There is, unfortunately, varying advice about this, especially on the web. I take the orthodox view that follows, which is from Oxford Dictionaries:

The general rule is that you should not use an apostrophe to form the plurals of nouns, abbreviations, or dates made up of numbers: just add -s (or -es, if the noun in question forms its plural with -es). For example: euros, pizzas, the 1990s.

There are one or two cases in which it is acceptable to use an apostrophe to form a plural, purely for the sake of clarity:

You can use an apostrophe to show the plurals of single letters: I've dotted the i's and crossed the t's; find all the p's in appear.

You can use an apostrophe to show the plurals of single numbers: find all the number 7’s. (Yes, this contradicts what I wrote above, where I said you shouldn't, You can do this, but you don't have to)

These are the only cases in which it is generally considered acceptable to use an apostrophe to form plurals. An apostrophe should never be used to form the plural of ordinary nouns, names, abbreviations, or numerical dates.

Note to the OP: TPG is an initialism, not an acronym. The difference is that acronyms are pronounced as words e.g. NATO, SCUBA, SIM, whereas an initialism is pronounced as the individual letters e.g. USA, BBC, NAACP.

I wonder what troll voted down my perfectly good, accurate and checkable advice?