Usage notes

* The first known use of the word"L. Feuchtwanger's Paris Gazette" (1940) used the word in the third sense: "Pee-gee-enn. It's an acronym [Ger. Akronym], that's what it is. That's what they call words made up of initials." * The third sense is sometimes criticized by commentators and others who prefer the term initialism for abbreviations that are not pronounced like an ordinary word, on the grounds that the distinction is useful. * An early definitionAmerican Speech Vol. 18, No. 2. (Apr., 1943), page 142 was "term for words made from the initial letters or syllables of other words", indicating that it should be pronounceable as a word, e.g. snafu, comsat. * Initialisms are generally written with all letters in upper case (such as EDP or IT). Acronyms are treated as words in their own right and are written in lower case (such as scuba or radar). * In American English, the general rule is that acronyms of more than four letters are written in lower case (e.g., laser, but UNESCO, UNHCR and many others) while those with four or fewer letters are written in all caps (e.g., NATO). (In European usage the latter example is usually written "Nato", it being both a true acronym and a proper noun.) * Older usage required that each letter be followed by a full stop (period). Current usage tends to omit full stops. * In recent years, the use of mixed capitalization in acronyms has become more common in two circumstances. The first occurs when the words contain articles that are not capitalized when spelled out in title case – for instance, Field of Regard initialized as "FoR." (This can be helpful in preventing confusion among acronyms spelled the same way to represent different meanings.) The other circumstance occurs when the writer is attempting to make an acronym pronounceable when it otherwise would not be by including more than just initial letters – for instance, "RaZR". * Acronyms also exist which, for convenience's sake, are pronounced with interstitial sounds, usually vowels, placed among the initials to make pronunciation easier. An example is WSDL (web services description language) pronounced wizdul .http://www.ibm.com/developerworks/library/lol/acronym.html