Abbreviation
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United States
Publications based in the U.S. tend to follow the style guides of the Chicago Manual of Style and the Associated Press.[verification needed] The U.S. Government follows a style guide published by the U.S. Government Printing Office.
However, there is some inconsistency in abbreviation styles, as they are not rigorously defined by style guides. Some two-word abbreviations, like "United Nations", are abbreviated with uppercase letters and periods, and others, like "personal computer" (PC) and "compact disc" (CD), are not; rather, they are typically abbreviated without periods and in uppercase letters. A third variation is to use lowercase letters with periods; this is used by Time Magazine in abbreviating "public relations" (p.r.). Moreover, even three-word abbreviations (most U.S. publications use uppercase abbreviations without periods) are sometimes not consistently abbreviated, even within the same article.
The New York Times is unique in having a consistent style by always abbreviating with periods: P.C., I.B.M., P.R. This is in contrast with the trend of British publications to completely make do without periods for convenience.
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Britain
Many British publications follow some of these guidelines in abbreviation:
- For the sake of convenience, many British publications, including the BBC and The Guardian, have completely done away with the use of full stops or periods in all abbreviations.
These include:
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- Social titles, like Ms or Mr (though these would usually not have had full stops — see above) Capt, Prof, etc.;
- Two-letter abbreviations for countries ("US", not "U.S.");
- Abbreviations beyond three letters (full caps for all except initialisms);
- Words seldom abbreviated with lower case letters ("PR", instead of "p.r.", or "pr")
- Names ("FW de Klerk", "GB Whiteley", "Park JS"). A notable exception is the newspaper The Economist which writes "Mr F. W. de Klerk".
- Scientific units (see Measurement below).
- Acronyms are often referred to with only the first letter of the abbreviation capitalised. For instance, the North Atlantic Treaty Organisation can be abbreviated as "Nato" or "NATO", and Severe Acute Respiratory Syndrome as "Sars" or "SARS" (compare with "laser" which has made the full transition to an English word and is rarely capitalised at all).
- Initialisms are always written in capitals; for example the "British Broadcasting Corporation" is abbreviated to "BBC", never "Bbc". An initialism is similar to acronym but is not pronounced as a word.
- When abbreviating scientific units, no space is added between the number and unit (100mph, 100m, 10cm, 10°C). (This is contrary to the SI standard, see below.)
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Miscellaneous and general rules
- Plurals are often formed by doubling the last letter of the abbreviation. Most of these deal with writing and publishing: MS=manuscript, MSS=manuscripts; l=line, ll=lines; p=page, pp=pages; s=section, ss=sections; op.=opus, opp.=opera. This form, derived from Latin is used in Europe in many places: dd=didots. "The following (lines or pages)" is denoted by "ff". One example that does not concern printing is hh=hands.
- A doubled letter also appears in abbreviations of some Welsh names, as in Welsh the double "l" is a separate sound: "Ll. George" for (British prime minister) Lloyd George.
- Some titles, such as "Reverend" and "Honourable", are spelt out when preceded by "the", rather than as "Rev." or "Hon." respectively. This is true for most British publications, and some in the United States.
- It is usually advised to spell out the abbreviation where it is new or unfamiliar to the reader (UNESCO in a magazine about music, because it refers to the United Nations Educational, Scientific and Cultural Organization, whose work does not concern the music).
- It is considered acceptable to start off a sentence with an abbreviation, however it is then advised to "ignore" the abbreviation and start the sentence as if it had begun with no abbreviation, but only if it is not the name of a person, place, or thing. For example, "BTW There is a new office manager." would be acceptable, though even without capping the "T", this instance is still accepted.
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Measurement
The International System of Units (SI) defines a set of base units, from which other "derived" units may be obtained. The abbreviations, or more accurately "symbols" (using Roman letters, or Greek in the case of ohm) for these units are also clearly defined together with a set of prefixes, themselves symbolised (abbreviated) with Roman letters (except only for micro, which uses the Greek letter µ), denoting powers of ten. The system is internationally recognized. Periods are not used, except as described below. Unit symbols do not have plural forms.
Units are written either in full, including the base units and their prefixes, or with all symbols. When a unit is written in full, it is written in all lower case. For example, megaampere for MA.
There should never be a period after or inside a unit; both '10 k.m.' and '10 k.m' are wrong — the only correct form is '10 km' (only followed with a period when at the end of a sentence).
A period "within" a compound unit denotes multiplication of the base units on each side of it. Ideally, this period should be raised to the centre of the line, but often it is not. For instance, '5 ms' means 5 millisecond(s), whereas '5 m.s' means 5 metre·second(s). The "m.s" here is a compound unit formed from the product of two fundamental SI units — metre and second.
There should always be a (non-breaking) space between the number and the unit — '25 km' is correct, and '25km' is incorrect. In Section 5.3.3. of The International System of Units (SI), the International Bureau of Weights and Measures (BIPM) states "The numerical value always precedes the unit, and a space is always used to separate the unit from the number. … The only exceptions to this rule are for the unit symbols for degree, minute, and second for plane angle."[3]
The case of letters (uppercase or lowercase) has meaning in the SI system, and should never be changed in a misguided attempt to follow an abbreviation style. For example, "10 S" denotes 10 siemens (a unit of conductance), while "10 s" denotes 10 seconds. Any unit named after a person is denoted by a symbol with an upper case first letter (S, Pa, A, V, N, Wb, W), but spelt out in full in lower case, (siemens, pascal, ampere, volt, newton, weber and watt). By contrast g, l, m, s, cd, ha represent gramme, litre, metre, second, candela and hectare respectively. The one slight exception to this rule is that the symbol for litre is allowed to be L to help avoid confusion with an upper case i or a one in some typefaces — compare l, I, and 1.
Likewise, the abbreviations of the prefixes denoting powers of ten are case-sensitive: m (milli) represents a thousandth, but M (mega) represents a million, so by inadvertent changes of case one may introduce (in this example) an error of a factor of 1 000 000 000. When a unit is written in full, the whole unit is written in lowercase, including the prefix: millivolt for mV, nanometre for nm, gigacandela for Gcd.
The above rules, if followed, ensure that the SI system is always unambiguous, so for instance mK denotes millikelvin, MK denotes megakelvin, K.m denotes kelvin.metre, and km denotes kilometre. Forms such as k.m and Km are ill-formed and technically meaningless in the SI system, although the intended meaning might be inferred from the context.
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See also
- List of classical abbreviations
- List of medieval abbreviations
- List of abbreviations in use in 1911
- List of acronyms and initialisms
- The abbreviations used in the 1913 edition of Webster's dictionary
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References
- ^ The Choctaw Expression 'Okeh' and the Americanism 'Okay'. Jim Fay (9/13/07). Retrieved on 2008-05-12.
- ^ What does "OK" stand for?. The Straight Dope. Retrieved on 2008-05-12.
- ^ The International System of Units (SI). International Bureau of Weights and Measures (BIPM). Retrieved on 2008-04-18.
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External links
- Abbreviations.com — a human edited database of acronyms and abbreviations
- United States Postal Services, (USPS), Street Abbreviations — USPS Street Abbreviations
- Acronym Finder — a human edited database of acronyms and abbreviations (over 550,000 entries)
- AuctionSlanguage.com — a human edited database of auction related acronyms and abbreviations
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