Editing 24-hour clock (section)

=== Military time ===
[[File:24-Hour Clock Aboard the USS Midway (8727193240).jpg|thumb|24-hour clock as seen on the [[USS Midway (CV-41)|USS Midway]].]]
In [[American English]], the term ''military time'' is a synonym for the 24-hour clock.<ref>{{Cite encyclopedia |url=http://www.lexico.com/definition/military_time |archive-url=https://web.archive.org/web/20201112033709/https://www.lexico.com/definition/military_time |url-status=dead |archive-date=12 November 2020 |title=military time |dictionary=[[Lexico]] UK English Dictionary |publisher=[[Oxford University Press]]}}</ref> In the US, the time of day is customarily given almost exclusively using the 12-hour clock notation, which counts the hours of the day as 12, 1, ..., 11 with suffixes ''a.m.'' and ''p.m.'' distinguishing the two [[Day|diurnal]] repetitions of this sequence. The 24-hour clock is commonly used there only in some specialist areas (military, aviation, navigation, tourism, meteorology, astronomy, computing, logistics, emergency services, hospitals), where the [[12-hour clock#Confusion at noon and midnight|ambiguities of the 12-hour notation]] are deemed too inconvenient, cumbersome, or dangerous.

Military usage, as agreed between the United States and allied English-speaking military forces,<ref>{{Cite web
| title=Communication Instructions General ACP 121(I)
| url=http://jcs.dtic.mil/j6/cceb/acps/acp121/ACP121I.pdf
| url-status=dead
| archive-url=https://web.archive.org/web/20160508202743/http://jcs.dtic.mil/j6/cceb/acps/acp121/ACP121I.pdf
| archive-date=8 May 2016
}}</ref> differs in some respects from other twenty-four-hour time systems:
*No hours/minutes separator is used when writing the time, and a [[Nautical time#Letter suffixes|letter designating the time zone]] is appended (for example "0340Z").
*[[Leading zero]]s are always written out and are required to be spoken, so 5:43&nbsp;a.m. is spoken "zero five forty-three" (casually) or "zero five four three" (military radio), as opposed to "five forty-three" or "five four three".
*[[List of military time zones|Military time zones]] are lettered and given word designations from the [[NATO phonetic alphabet]]. For example, in [[Eastern Time Zone|US Eastern Standard Time]] (UTC−5), which is designated time zone R, 2:00&nbsp;a.m. is written "0200R" and spoken "zero two hundred Romeo".
*Local time is designated as zone J or "[[NATO phonetic alphabet|Juliett]]". "1200J" ("twelve hundred Juliett") is noon local time.
*[[Greenwich Mean Time]] (GMT) or [[Coordinated Universal Time]] (UTC) is designated time zone Z, and thus called "Zulu time". (When used as a modern time zone, in practice, GMT and UTC coincide. For other purposes there may be a difference of about a second.<ref>{{Cite journal| last1 = Guinot| first1 = Bernard | date = August 2011 | volume=48 | issue=4 | title = Solar time, legal time, time in use | journal = Metrologia | page =185 | doi = 10.1088/0026-1394/48/4/S08|bibcode = 2011Metro..48S.181G| s2cid = 121852011 }}</ref>)
*Hours are always "hundred", never "thousand"; 1000 is "ten hundred" not "one thousand"; 2000 is "twenty hundred" not "two thousand".