Representing plurals and possessives
The traditional style of pluralizing single letters with the addition of ’s (for example, B’s come after A’s) was extended to some of the earliest initialisms, which tended to be written with periods to indicate the omission of letters; some writers still pluralize initialisms in this way. Some style guides continue to require such apostrophes—perhaps partly to make it clear that the lower case s is only for pluralization and would not appear in the singular form of the word, for some acronyms and abbreviations do include lowercase letters.
However, it has become common among many writers to inflect initialisms as ordinary words, using simple s, without an apostrophe, for the plural. In this case, compact discs becomes CDs. The logic here is that the apostrophe should be restricted to possessives: for example, the CD’s label (the label of the compact disc).[16]
Multiple options arise when initialisms are spelled with periods and are pluralized: for example, compact discs may become C.D.’s, C.D’s, C.D.s, or CDs. Possessive plurals that also include apostrophes for mere pluralization and periods may appear especially complex: for example, the C.D.’s’ labels (the labels of the compact discs). Some see this as yet another reason that the correct usage of apostrophes is only for possessives and not for plurals. In some instances, however, it is recognized that using an apostrophe can increase clarity, for example if the final letter of an acronym is an S, as in SOS's, or when writing the plural form of an abbreviation with periods[17] [18] (In The New York Times, the plural possessive of G.I., which the newspaper prints with periods in reference to United States Army soldiers, is G.I.’s, with no apostrophe after the s.)
A particularly rich source of options arises when the plural of an initialism would normally be indicated in a word other than the final word if spelled out in full. A classic example is Member of Parliament, which in plural is Members of Parliament. It is possible then to abbreviate this as M’s P. [19] [20] (or similar [21]), as famously by a former Australian Prime Minister [22]. This usage is less common than forms with "s" at the end, such as MPs, and may appear dated or pedantic.
The argument that initialisms should have no different plural form (for example, "If D can stand for disc, it can also stand for discs") is generally disregarded because of the practicality in distinguishing singulars and plurals. This is not the case, however, when the abbreviation is understood to describe a plural noun already: for example, U.S. is short for United States, but not United State. In this case, the options for making a possessive form of an abbreviation that is already in its plural form without a final s may seem awkward: for example, U.S.’, U.S’, U.S.’s, etc. In such instances, possessive abbreviations are often foregone in favor of simple attributive usage (for example, the U.S. economy) or expanding the abbreviation to its full form and then making the possessive (for example, the United States' economy). On the other hand, in colloquial speech the pronunciation United States’s is sometimes used.
Abbreviations that come from single, rather than multiple, words—such as TV (television)—are pluralized both with and without apostrophes, depending on the logic followed: that the apostrophe shows the omission of letters and makes the s clear as only a pluralizer (TV’s); or that the apostrophe should be reserved for the possessive (TVs).
In some languages, the convention of doubling the letters in the initialism is used to indicate plural words: for example, the Spanish EE.UU., for Estados Unidos (United States). This convention is followed for a limited number of English abbreviations, such as pp. for pages (although this is actually derived from the Latin abbreviation for paginae), or MM for millions (frequently used in the petroleum industry).
Acronyms that are now always rendered in the lower case are pluralized as regular English nouns: for example, lasers.
When an initialism is part of a function in computing that is conventionally written in lower case, it is common to use an apostrophe to pluralize or otherwise conjugate the token. This practice results in sentences like "Be sure to remove extraneous dll’s" (more than one dll). However despite the pervasiveness of this practice, it is generally held to be technically incorrect; the preferred method being to simply append an s, without the apostrophe. [23]
In computer lingo, it is common to use the name of a computer program, format, or function, acronym or not, as a verb. In such verbification of abbreviations, there is confusion about how to conjugate: for example, if the verb IM (pronounced as separate letters) means to send (someone) an instant message, the past tense may be rendered IM’ed, IMed, IM’d, or IMd—and the third-person singular present indicative may be IM’s or IMs.
