Plurals and Possessives

Part of my job at work is to review other people's work. Lately at work, but also online, in print media, and on TV, I have seen a plethora of acronyms made plural using an apostrophe and an s. So much so that I was starting to question my memory of what is correct! I grabbed our copy of the Microsoft Manual of Style, our bible on the job, and reviewed possessives and plurals as they relate to acronyms.

It says that acronyms are made plural by simply adding an s on the end, unless one of the abbreviated words is a plural form already-- then you don't add an s.

Correct
SUVs
CPUs
RBI (Runs Batted in-- run is already a plural)

Incorrect
SUV's
CPU's
RsBI or RBIs

This is also true of numbers.

Correct
1950s
486s

The only time you add an apostrophe to form a plural is when using a single letter. However, in addition to the apostrophe and s, the root letter should be in italics (but nothing else). Although the manual doesn't say it, I believe this is so that it doesn't look like you are forming a new acronym ( i.e., "x's" lets you see that x is the root letter, while "xs," even with the italicized root letter, tends to look like an acronym involving two words, one started with an x and the other starting with an s).

Correct
x's

Form the possessive by adding apostrophe and an s unless the word ends in an s already; then, you simply add the apostrophe. When forming possessives of an acronym, you should only use the possessive when the abbreviation refers to a person ( i.e., CEO) or generically to an organization (i.e., OEM). You should avoid using possessives, by the way, for company, product, or feature names.

Correct
The CEO's desk
The OEM's products (possessive of a generic organization)
The OEMs' products (plural and possessive of a generic organization)
The Windows interface
Microsoft products and technologies
The Search field entry

Incorrect
The CPU's L2 cache (not a person or generic organization-- use of construction instead; The L2 cache of the CPU)
The SUV's wheelbase
Windows' interface (product name)
Microsoft's products and technologies (company name)
the Search field's entry (specific feature)


Now, I let myself slack on many rules and formalities while writing personal emails and this blog, as I am not being paid to do either and the repercussions for errors are relatively low. I know, for example, that I have used "CPU's" in the past to add possession to an acronym that didn't warrant it.

It is nice that what I knew to be correct is, in fact, still the correct way to write. However, I am still left with the thought: Why am I seeing this particular mistake so much right now?