ENGLISH LANGUAGE PUNCTUATION MARKS

Colon

4. English Language Punctuation - Colon

The function of the colon is to separate and introduce lists, clauses, and quotations, along with several conventional uses. Authorities disagree on usage of the colon and capitalization after a colon. The following guidelines generally correspond to Words Into Type (Skillin et al. 1974).

4. a) English Language Punctuation - Colons That Introduce

A colon has the same separating force as a period. It thus brings a sentence almost to a halt (Bernstein 1981). Because of its strong separating function, an introductory colon should generally be used only after a complete sentence. In particular, do not use a colon between a verb or preposition and its direct object: Wrong Correct Wrong Correct The components of the rack-mounted electronics are: power supplies, the gimbal controller, . . . The components of the rack-mounted electronics are power supplies, the gimbal controller, . . . The scatterometer is separated into: a gimbal, a transmitterreceiver assembly, and rack-mounted electronics. The scatterometer is separated into a gimbal, a transmitterreceiver assembly, and rack-mounted electronics.

Nor should a colon be used after such introductory phases as that is, for example, and such as (the colon replaces them): Wrong Either Or Microwave instruments are used for remote sensing of environmental variables such as: sea ice, soil moisture, and surface wind speed. Microwave instruments are used for remote sensing of environmental variables, such as sea ice, soil moisture, and surface wind speed. Microwave instruments are used for remote sensing of environmental variables: sea ice, soil moisture, and surface wind speed.

When items of a list are numbered, the numbers do not affect the punctuation: The quantities calculated from microwave instruments are (a) radiometer wind speed, (b) radiometer rain rate, and (c) scatterometer wind vector. Remember that the colon has strong separating force; do not use it where separation is not grammatically desirable. When using a colon incorrectly, an author probably wants to emphasize the material that follows. The editor should consider a correction that preserves this emphasis, for example, itemization or correct use of the colon. Lists A colon is an elegant way of introducing a list and at the same time emphasizing the elements of the list (by separating them from the rest of the sentence). Such lists might consist of words, phrases (prepositional, infinitive, or noun), or even clauses. Use a colon to introduce a list in apposition to a noun: The scatterometer is separated into three assemblies: a gimbal, a transmitter-receiver assembly, and rack-mounted electronics. Use a colon to introduce a list whose introductory statement contains the words as follows or the following: The rack-mounted electronics consist of the following: power supplies, the gimbal controller, . . . Use a colon to introduce a list that amplifies an introductory sentence: The purpose of this report is twofold: to evaluate the performance of the instruments and to expand the data base. One very effective way to emphasize a list, and at the same time make a long list easy to read, is to number and display the list: The scatterometer is separated into three assemblies:

Punctuation - A gimbal A transmitter-receiver assembly Rack-mounted electronics

When the introduction to a displayed list is not a complete sentence (the items of the list complete it), no colon is used (Chicago Press 1982; and Skillin et al. 1974): The purposes of this report are 1. English Language Punctuation - 2. English Language Punctuation - To evaluate the performance of the instruments To expand the data base

There is a trend toward using a colon after a verb preceding a displayed list (are in the above example). Such use of the colon is grammatically suspect and unnecessary. Clauses A colon may be used between two clauses when the second amplifies or restates the first, for example, The toughness of pseudo-maraging steel degrades at cryogenic temperatures: at -320 deg F, its Charpy impact energy is 6 ft-lb. Note: The first word after a colon may be capital only when the capital begins a complete sentence; however, capitalization of a complete sentence after a colon is optional. The dash and semicolon may also be used in this situation. The colon is more formal than the dash and has more introductory force than the semicolon. A colon is particularly useful for introducing displayed equations (which can be considered clauses), particularly when the equation symbolically restates the preceding sentence: The out-of-plane deflection w o can be approximated by a truncated kinematically admissable series: wo Quotations A colon may be used to introduce a direct quotation, particularly if the quote is long (more than one sentence) or not built closely into the sentence (Ebbitt and Ebbitt 1982): In reference 6, he states this conclusion: "Thermal neutron fluxes up to 1020 might be required." However, a comma is usually sufficient for direct quotations: In reference 6, he states, "Thermal neutron fluxes up to 1020 might be required." Neither a colon nor a comma should be used before an indirect quotation: In reference 6, he concludes that thermal neutron fluxes up to 1020 might be required. w 2k -1 cos [(2k -1) ]

4. b) English Language Punctuation - Conventional Uses of the Colon

The colon is used by convention as follows: After the salutation in formal letters: Dear Sir: Between hours and minutes in time: 11:30 a.m. In reference citations: Slater, Philip N.: Remote Sensing . . . To express ratios: 2:1 mixture

4. c) English Language Punctuation - Use With Other Marks

A colon follows closing parentheses and closing quotation marks.