Manual of style/Time and date

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Precise language

Avoid statements that will age quickly, except on pages concerning current events which are frequently brought up to date. Avoid recently, soon, and now (unless their meaning is fixed by the context). Avoid relative terms like currently (usually redundant), in modern times, is now considered, and is soon to be superseded. Instead, use either:

• more precise and absolute expressions (since the start of 2005; during the 1990s; is expected to be superseded by 2008); or
• an as of phrase (as of August 2007), which signals the time-dependence of the statement, and alerts later editors to update the statement (see As of); or simply use at instead: The population was over 21,000,000 (at December 2008).

Times

Context determines whether the 12-hour clock or 24-hour clock is used; in both, colons separate hours, minutes, and seconds (1:38:09 pm and 13:38:09).

• 12-hour clock times should end with dotted lower-case a.m. or p.m., which are spaced (2:30 p.m., not 2:30p.m.). A hard space is advisable: 2:30 pm. Use noon and midnight rather than 12 p.m. and 12 a.m.; whether midnight refers to the start or the end of a date will need to be specified unless this is clear from the context.
• 24-hour clock times have no a.m., p.m., noon, or midnight suffix. Use discretion as to whether the hour has a leading zero (08:15 or 8:15). 00:00 refers to midnight at the start of a date, 12:00 to noon, and 24:00 to midnight at the end of a date.

Dates

• Retro does not add ordinal suffixes (such as -nd) or the, or put a comma between month and year.

Incorrect:	February 14th, 14th February, the 14th of February
Correct:	14 February, February 14
Incorrect:	October, 1976; October of 1976
Correct:	October 1976

• As a quick and dirty rule, use month before day in breakout boxes or for general use in an article; move to day before month when discussing dates relative to a country using such syntax.
• Dates are not linked.
• Date ranges are preferably given with minimal repetition, using an unspaced en dash where the range involves numerals alone (5–7 January 1979; January 5–7, 2002) or a spaced en dash where both the opening and the closing date have internal spaces (5 January – 18 February 1979; January 5 – February 18, 1979).
• Rarely, a night may be expressed in terms of the two contiguous dates using a slash (the bombing raids of the night of 30/31 May 1942).
• Yearless dates (5 March, March 5) are inappropriate unless the year is obvious from the context. There is no such ambiguity with recurring dates, such as January 1 is New Year's Day.
• Dates in the format YYYY-MM-DD (like 1976-05-13) are uncommon in English prose and are generally not used in article prose. However, they may be useful in long lists, references, and tables for conciseness and ease of comparison.

Longer periods

• Write months as whole words (February, not 2), except in the YYYY-MM-DD format (as in 2000-04-01). Use abbreviations such as Feb. only where space is extremely limited, such as in tables and breakout boxes. Do not insert of between a month and a year (April 2000, not April of 2000).
• Seasons as dates. As the seasons are reversed in the northern and southern hemispheres—and areas near the equator tend to have just wet and dry seasons—neutral wording (in early 1990, in the second quarter of 2003, around September) is usually preferable to a "seasonal" reference (summer 1918, spring 1995). Even when the season reference is unambiguous (for instance when a particular location is clearly involved) a date or month may be preferable to a season name, unless there is a logical connection (the autumn harvest). Season names are preferable, however, when they refer to a phase of the natural yearly cycle (migration to higher latitudes typically starts in mid-spring).
• Season names are not normally capitalized.
• Years
  • Years are normally expressed in digits; a comma is not used in four-digit years (1988, not 1,988).
  • A slash may be used to indicate regular defined yearly periods that do not coincide with calendar years (the financial year 1993/94).
• Decades contain no apostrophe (the 1980s, not the 1980's); the two-digit form is used only where the century is clear (the '80s or the 80s).