yeahI was just backing you up - as is this webpage:
Plural and Possessive Abbreviations
The formation of plurals and possessives is usually pretty straightforward, except in the case of abbreviations and acronyms. The following rules should help.
To form the plural of an abbreviation, a number, or a capital letter used as a noun, simply add an 's' to the end.
* A group of MPs
* The late 1940s
* Mind your Ps and Qs
To form the plural of an abbreviation with periods, a lowercase letter used as a noun, and abbreviations or capital letters that would be ambiguous or confusing if the 's' alone were added, use an apostrophe and an 's'.
* A group of M.P.'s (see note below)
* The x's in the equation
* Sending SOS's
Edit: I just reread that - and it kinda shows the other way is right...
(,
Tue 27 Sep 2005, 12:58,
archived)
Plural and Possessive Abbreviations
The formation of plurals and possessives is usually pretty straightforward, except in the case of abbreviations and acronyms. The following rules should help.
To form the plural of an abbreviation, a number, or a capital letter used as a noun, simply add an 's' to the end.
* A group of MPs
* The late 1940s
* Mind your Ps and Qs
To form the plural of an abbreviation with periods, a lowercase letter used as a noun, and abbreviations or capital letters that would be ambiguous or confusing if the 's' alone were added, use an apostrophe and an 's'.
* A group of M.P.'s (see note below)
* The x's in the equation
* Sending SOS's
Edit: I just reread that - and it kinda shows the other way is right...