A

A.M., P.M.

International considerations

To accommodate the worldwide audience, use the 24-hour time notation if you can. Use 00:00, not 24:00, to indicate midnight. If you must use A.M. and P.M., use capital letters and periods.

Using 12:00 A.M. or 12:00 P.M. to refer to noon or midnight is confusing. If you are consistently using 24-hour notation, 00:00 and 12:00 are unambiguous. In any case, just specifying noon or midnight is sufficient.

Microsoft style

The meeting is at noon.

The show begins at 19:00 Pacific Time (UTC-8).

The date changes at exactly midnight.

See also midnight, Time zones.

-able, -ible

Adjectives ending in -able or -ible take their meaning from the passive sense of the stem verb from which they are formed. For example, forgettable ...

Get Microsoft® Manual of Style, Fourth Edition now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.