12-hour clock

Last updated

The 12-hour clock is a time convention in which the 24 hours of the day are divided into two periods: a.m. (from Latin ante meridiem, translating to "before midday") and p.m. (from Latin post meridiem, translating to "after midday"). [1] [2] Each period consists of 12 hours numbered: 12 (acting as 0), [3] 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11. The 12-hour clock has been developed since the second millennium BC and reached its modern form in the 16th century.

Contents

The 12-hour time convention is common in several English-speaking nations and former British colonies, as well as a few other countries. There is no widely accepted convention for how midday and midnight should be represented: in English-speaking countries, "12 p.m." indicates 12 o'clock noon, while "12 a.m." means 12 o'clock midnight. [4] [5] [6]

Clock system
12-hour 24-hour
Midnight (start of day)
12 midnight
12:00 a.m. [lower-alpha 1] 		00:00
12:01 a.m.00:01
 1:00 a.m.01:00
11:00 a.m.11:00
11:59 a.m.11:59
Noon
12 noon
12:00 p.m. [lower-alpha 1] 		12:00
12:01 p.m.12:01
 1:00 p.m.13:00
11:00 p.m.23:00
11:59 p.m.23:59
Midnight (end of day)
or shown as start of next day [lower-alpha 1] 		24:00

(00:00)

History and use

Exeter Cathedral Astronomical Clock, showing the double-XII numbering scheme Exeter Cathedral astronomical clock.jpg
Exeter Cathedral Astronomical Clock, showing the double-XII numbering scheme

The natural day-and-night division of a calendar day forms the fundamental basis as to why each day is split into two cycles. Originally there were two cycles: one cycle which could be tracked by the position of the Sun (day), followed by one cycle which could be tracked by the Moon and stars (night). This eventually evolved into the two 12-hour periods which are used today, one called "a.m." starting at midnight and another called "p.m." starting at noon. Noon itself is rarely abbreviated today; but if it is, it is denoted "m." [1]

The 12-hour clock can be traced back as far as Mesopotamia and ancient Egypt. [7] Both an Egyptian sundial for daytime use [8] and an Egyptian water clock for night-time use were found in the tomb of Pharaoh Amenhotep I. [9] Dating to c. 1500 BC, these clocks divided their respective times of use into 12 hours each.

The Romans also used a 12-hour clock: daylight was divided into 12 equal hours (thus hours having varying length throughout the year) and the night was divided into four watches.[ citation needed ]

The first mechanical clocks in the 14th century, if they had dials at all, showed all 24 hours using the 24-hour analog dial, influenced by astronomers' familiarity with the astrolabe and sundial and by their desire to model the Earth's apparent motion around the Sun. In Northern Europe these dials generally used the 12-hour numbering scheme in Roman numerals but showed both a.m. and p.m. periods in sequence. This is known as the double-XII system and can be seen on many surviving clock faces, such as those at Wells and Exeter.

Elsewhere in Europe, numbering was more likely to be based on the 24-hour system (I to XXIV). The 12-hour clock was used throughout the British empire.

During the 15th and 16th centuries, the 12-hour analog dial and time system gradually became established as standard throughout Northern Europe for general public use. The 24-hour analog dial was reserved for more specialized applications, such as astronomical clocks and chronometers.

Most analog clocks and watches today use the 12-hour dial, on which the shorter hour hand rotates once every 12 hours and twice in one day. Some analog clock dials have an inner ring of numbers along with the standard 1-to-12 numbered ring. The number 12 is paired either with a 00 or a 24, while the numbers 1 through 11 are paired with the numbers 13 through 23, respectively. This modification allows the clock to also be read in 24-hour notation. This kind of 12-hour clock can be found in countries where the 24-hour clock is preferred.

Use by country

Typical analogue 12-hour clock Westclox Big Ben.jpg
Typical analogue 12-hour clock
World map showing the usage of 12 or 24-hour clock in different countries .mw-parser-output .legend{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .legend-color{display:inline-block;min-width:1.25em;height:1.25em;line-height:1.25;margin:1px 0;text-align:center;border:1px solid black;background-color:transparent;color:black}.mw-parser-output .legend-text{} 24-hour 24-hour (12-hour orally) Both in common use 12-hour 12 24 Hours World Map.svg
World map showing the usage of 12 or 24-hour clock in different countries
  24-hour
  24-hour (12-hour orally)
  Both in common use
  12-hour

In several countries the 12-hour clock is the dominant written and spoken system of time, predominantly in nations that were part of the former British Empire, for example, the United Kingdom, Republic of Ireland, the United States, Canada (excluding Quebec), Australia, New Zealand, South Africa, India, Pakistan, and Bangladesh, and others follow this convention as well, such as Mexico and the former American colony of the Philippines. In most countries, however, the 24-hour clock is the standard system used, especially in writing. Some nations in Europe and Latin America use a combination of the two, preferring the 12-hour system in colloquial speech but using the 24-hour system in written form and in formal contexts.

The 12-hour clock in speech often uses phrases such as ... in the morning, ... in the afternoon, ... in the evening, and ...at night. Rider's British Merlin almanac for 1795 and a similar almanac for 1773 published in London used them. [10] Other than in English-speaking countries and some Spanish-speaking countries, the terms a.m. and p.m. are seldom used and often unknown.

Computer support

In most countries, computers by default show the time in 24-hour notation. Most operating systems, including Microsoft Windows and Unix-like systems such as Linux and macOS, activate the 12-hour notation by default for a limited number of language and region settings. This behaviour can be changed by the user, such as with the Windows operating system's "Region and Language" settings. [11]

Abbreviations

Typical digital 12-hour alarm clock indicating p.m. with a dot to the left of the hour Digital-clock-alarm.jpg
Typical digital 12-hour alarm clock indicating p.m. with a dot to the left of the hour

The Latin abbreviations a.m. and p.m. (often written "am" and "pm", "AM" and "PM", or "A.M." and "P.M.") are used in English and Spanish. [12] The equivalents in Greek are π.μ. and μ.μ., respectively, and in Sinhala පෙ.ව. (pe.va.) for පෙරවරු (peravaru, පෙරpera – fore, pre) and ප.ව. (pa.va.) for පස්වරු (pasvaru, පස්සේpassē – after, post). However, noon is rarely abbreviated in either of these languages, noon normally being written in full. In Portuguese, there are two official options and many others used, for example, using 21:45, 21h45 or 21h45min (official ones) or 21:45 or 9:45 p.m. In Irish, a.m. and i.n. are used, standing for ar maidin ("in the morning") and iarnóin ("afternoon") respectively.

Most other languages lack formal abbreviations for "before noon" and "after noon", and their users use the 12-hour clock only orally and informally.[ citation needed ] However, in many languages, such as Russian and Hebrew, informal designations are used, such as "9 in the morning" or "3 in the night".

When abbreviations and phrases are omitted, one may rely on sentence context and societal norms to reduce ambiguity. For example, if one commutes to work at "9:00", 9:00 a.m. may be implied, but if a social dance is scheduled to begin at "9:00", it may begin at 9:00 p.m.

Typography

The terms "a.m." and "p.m." are abbreviations of the Latin ante meridiem (before midday) and post meridiem (after midday). Depending on the style guide referenced, the abbreviations "a.m." and "p.m." are variously written in small capitals ("am" and "pm"),[ citation needed ] uppercase letters without a period ("AM" and "PM"), uppercase letters with periods, or lowercase letters ("am" and "pm" or, [13] "a.m." and "p.m.").[ citation needed ] With the advent of computer generated and printed schedules, especially airlines, advertising, and television promotions, the "M" character is often omitted as providing no additional information as in "9:30A" or "10:00P". [14]

Some style guides suggest the use of a space between the number and the a.m. or p.m. abbreviation.[ citation needed ] Style guides recommend not using a.m. and p.m. without a time preceding it. [15]

The hour/minute separator varies between countries: some use a colon, others use a period (full stop), [13] and still others use the letter h.[ citation needed ] (In some usages, particularly "military time", of the 24-hour clock, there is no separator between hours and minutes. [16] This style is not generally seen when the 12-hour clock is used.)

Encoding

Unicode specifies codepoints for "a.m." and "p.m." symbols, which are intended to be used only with Chinese-Japanese-Korean (CJK) character sets, as they take up exactly the same space as one CJK character:

Informal speech and rounding off

In speaking, it is common to round the time to the nearest five minutes and/or express the time as the past (or to) the closest hour; for example, "five past five" (5:05). Minutes past the hour means those minutes are added to the hour; "ten past five" means 5:10. Minutes to, 'til and of the hour mean those minutes are subtracted; "ten of five", "ten 'til five", and "ten to five" all mean 4:50.

Fifteen minutes is often called a quarter hour, and thirty minutes is often known as a half hour. For example, 5:15 can be phrased "(a) quarter past five" or "five-fifteen"; 5:30 can be "half past five", "five-thirty" or simply "half five". The time 8:45 may be spoken as "eight forty-five" or "(a) quarter to nine". [17]

In older English, it was common for the number 25 to be expressed as "five-and-twenty". [18] In this way the time 8:35 may be phrased as "five-and-twenty to 9", [19] although this styling fell out of fashion in the later part of the 1900s and is now rarely used. [20]

Instead of meaning 5:30, the "half five" expression is sometimes used to mean 4:30, or "half-way to five", especially for regions such as the American Midwest and other areas that have been particularly influenced by German culture.[ citation needed ] This meaning follows the pattern choices of many Germanic and Slavic languages, including Serbo-Croatian, Dutch, Danish, Russian and Swedish, as well as Hungarian, Finnish and the languages of the Baltic States.

Moreover, in situations where the relevant hour is obvious or has been recently mentioned, a speaker might omit the hour and just say "quarter to (the hour)", "half past" or "ten 'til" to avoid an elaborate sentence in informal conversations. These forms are often commonly used in television and radio broadcasts that cover multiple time zones at one-hour intervals. [21]

In describing a vague time of day, a speaker might say the phrase "seven-thirty, eight" to mean sometime around 7:30 or 8:00. Such phrasing can be misinterpreted for a specific time of day (here 7:38), especially by a listener not expecting an estimation. The phrase "about seven-thirty or eight" clarifies this.

Some more ambiguous phrasing might be avoided. Within five minutes of the hour, the phrase "five of seven" (6:55) can be heard "five-oh-seven" (5:07). "Five to seven" or even "six fifty-five" clarifies this.

Formal speech and times to the minute

Minutes may be expressed as an exact number of minutes past the hour specifying the time of day (e.g., 6:32 p.m. is "six thirty-two"). Additionally, when expressing the time using the "past (after)" or "to (before)" formula, it is conventional to choose the number of minutes below 30 (e.g., 6:32 p.m. is conventionally "twenty-eight minutes to seven" rather than "thirty-two minutes past six").

In spoken English, full hours are often represented by the numbered hour followed by o'clock (10:00 as ten o'clock, 2:00 as two o'clock). This may be followed by the "a.m." or "p.m." designator, though some phrases such as in the morning, in the afternoon, in the evening, or at night more commonly follow analog-style terms such as o'clock, half past three, and quarter to four. O'clock itself may be omitted, telling a time as four a.m. or four p.m. Minutes ":01" to ":09" are usually pronounced as oh one to oh nine (nought or zero can also be used instead of oh). Minutes ":10" to ":59" are pronounced as their usual number-words. For instance, 6:02 a.m. can be pronounced six oh two a.m. whereas 6:32 a.m. could be told as six thirty-two a.m.

Confusion at noon and midnight

Time according to various conventions
Device or style Midnight
Start of day		 Noon Midnight
End of day
Written 24-hour time00:0012:0024:00
Digital watches (12-hour)12:00 AM12:00 PM12:00 AM
Digital watches (24-hour)0:0012:000:00
U.S. Government Publishing Office (1953) [22] midnight [lower-alpha 1] noon
12 o'clock noon
12 m.		midnight [lower-alpha 1]
12:00 p.m.
U.S. Government Publishing Office (2000) [23]  
midnight [lower-alpha 1] 		12 a.m.
noon		12 p.m.
midnight [lower-alpha 1]
U.S. Government Publishing Office (2008) [24] 12 a.m.
12 midnight [lower-alpha 1] 		12 p.m.
12 noon		 
12 midnight [lower-alpha 1]
Japanese legal convention [25] 午前0時 (0 a.m.)午前12時 (12 a.m.)午後12時 (12 p.m.)
Japanese common usage [26] 午前0時 (0 a.m.)午後0時 (0 p.m.)午後12時 (12 p.m.)
Chicago Manual of Style [27] noon
12:00 m.
Canadian Press, [28] UK standard [29] MidnightNoonMidnight
Associated Press style [30] —noonmidnight
NIST [2] midnight [lower-alpha 2]
12:01 a.m.		noonmidnight [lower-alpha 2]
11:59 p.m.
  1. 1 2 3 4 5 6 These styles are ambiguous with respect to whether midnight is at the start or end of each day.
  2. 1 2 NIST recommends using 11:59 p.m. and 12:01 a.m. to disambiguate when needed.

It is not always clear what times "12:00 a.m." and "12:00 p.m." denote. From the Latin words meridies (midday), ante (before) and post (after), the term ante meridiem (a.m.) means before midday and post meridiem (p.m.) means after midday. Since "noon" (midday, meridies (m.)) is neither before nor after itself, the terms a.m. and p.m. do not apply. [2] Although "12 m." was suggested as a way to indicate noon, this is seldom done [27] and also does not resolve the question of how to indicate midnight.

The American Heritage Dictionary of the English Language states "By convention, 12 AM denotes midnight and 12 PM denotes noon. Because of the potential for confusion, it is advisable to use 12 noon and 12 midnight." [31]

E. G. Richards in his book Mapping Time (1999) provided a diagram in which 12 a.m. means noon and 12 p.m. means midnight. [32]

Historically, the style manual of the United States Government Printing Office used 12 a.m. for noon and 12 p.m. for midnight until its 2008 edition. At this point it reversed these designations [23] [24] and then retained that change in its 2016 revision. [33]

Many U.S. style guides, and NIST's "Frequently asked questions (FAQ)" web page, [2] recommend that it is clearest if one refers to "noon" or "12:00 noon" and "midnight" or "12:00 midnight" (rather than to "12:00 p.m." and "12:00 a.m."). The NIST website states that "12 a.m. and 12 p.m. are ambiguous and should not be used."

The Associated Press Stylebook specifies that midnight "is part of the day that is ending, not the one that is beginning." [30]

The Canadian Press Stylebook [28] says, "write noon or midnight, not 12 noon or 12 midnight." Phrases such as "12 a.m." and "12 p.m." are not mentioned at all.

In the UK, the National Physical Laboratory "FAQ-Time" web page [29] states "In cases where the context cannot be relied upon to place a particular event, the pair of days straddling midnight can be quoted"; also "the terms 12 a.m. and 12 p.m. should be avoided."

Likewise, some U.S. style guides recommend either clarifying "midnight" with other context clues, such as specifying the two dates between which it falls, or not referring to the term at all. For an example of the latter method, "midnight" is replaced with "11:59 p.m." for the end of a day or "12:01 a.m." for the start of a day. That has become common in the United States in legal contracts and for airplane, bus, or train schedules, though some schedules use other conventions. Occasionally, when trains run at regular intervals, the pattern may be broken at midnight by displacing the midnight departure one or more minutes, such as to 11:59 p.m. or 12:01 a.m. [34]

In Japanese usage, midnight is written as 午前0時 (0 a.m.) and noon is written as 午後0時 (0 p.m.), making the hours numbered sequentially from 0 to 11 in both halves of the day. Alternatively, noon may be written as 午前12時 (12 a.m.) and midnight at the end of the day as 午後12時 (12 p.m.), as opposed to 午前0時 (0 a.m.) for the start of the day, making the Japanese convention the opposite of the English usage of 12 a.m. and 12 p.m. [26]

See also

Related Research Articles

<span class="mw-page-title-main">Hour</span> Unit of time equal to 60 minutes

An hour is a unit of time historically reckoned as 1⁄24 of a day and defined contemporarily as exactly 3,600 seconds (SI). There are 60 minutes in an hour, and 24 hours in a day.

<span class="mw-page-title-main">Time signal</span> Signal used as a reference to determine the time of day

A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day.

<span class="mw-page-title-main">Noon</span> 12 oclock in the daytime

Noon is 12 o'clock in the daytime. It is written as 12 noon, 12:00 m., 12 p.m., 12 pm, or 12:00 or 1200 . Solar noon is the time when the Sun appears to contact the local celestial meridian. This is when the Sun reaches its apparent highest point in the sky, at 12 noon apparent solar time and can be observed using a sundial. The local or clock time of solar noon depends on the date, longitude, and time zone, with Daylight Saving Time tending to place solar noon closer to 1:00pm.

<span class="mw-page-title-main">24-hour clock</span> Timekeeping convention

The modern 24-hour clock is the convention of timekeeping in which the day runs from midnight to midnight and is divided into 24 hours. This is indicated by the hours passed since midnight, from 00(:00) to 23(:59), with 24(:00) as an option to indicate the end of the day. This system, as opposed to the 12-hour clock, is the most commonly used time notation in the world today, and is used by the international standard ISO 8601.

<span class="mw-page-title-main">Midnight</span> Transition time from one day to the next

Midnight is the transition time from one day to the next – the moment when the date changes, on the local official clock time for any particular jurisdiction. By clock time, midnight is the opposite of noon, differing from it by 12 hours.

<span class="mw-page-title-main">Analog watch</span>

An analog watch (American) or analogue watch is a watch whose display is not digital but rather analog with a traditional clock face. The name is an example of a retronym; it was coined to distinguish analog watches, which had simply been called "watches", from newer digital watches. It strictly refers to the design of the display, regardless of the timekeeping technology used within the watch movement or module, although its counterpart, "digital watch", usually connotes digital electronics in both. A digital watch is one in which the time is displayed as a series of digits, e.g. "04:32". An analog watch is one in which the display is not digital, but is indicated (typically) by the continuous motion of one, two, or three rotating pointers or hands pointing to numbers arrayed on a circular dial.

<span class="mw-page-title-main">24-hour analog dial</span> Clock or watch face showing the full 24 hours

Clocks and watches with a 24-hour analog dial have an hour hand that makes one complete revolution, 360°, in a day. The more familiar 12-hour analog dial has an hour hand that makes two complete revolutions in a day.

<span class="mw-page-title-main">Philippine Standard Time</span> Time zone used in the Philippines (UTC+08:00)

Philippine Standard Time, also known as Philippine Time (PHT), is the official name for the time zone used in the Philippines. The country only uses a single time zone, at an offset of UTC+08:00, but has used daylight saving time for brief periods in the 20th century until July 28, 1990.

Different conventions exist around the world for date and time representation, both written and spoken.

<span class="mw-page-title-main">Kremlin Clock</span> Historic clock on the Spasskaya Tower

The Kremlin Clock or Kremlin Chimes, also known colloquially in the West as Moscow Clock Tower, is a historic clock on the Spasskaya Tower of Moscow Kremlin. The clock dial is above the main gates to Red Square. For decades, the chimes have rung on the quarter-hour, with bells tolling for each full hour.

Date and time notation in the United States differs from that used in nearly all other countries. It is inherited from one historical branch of conventions from the United Kingdom. American styles of notation have also influenced customs of date notation in Canada, creating confusion in international commerce.

In Poland, the official system for representing dates and times follows the international ISO 8601 standard. However, in less official use, other conventions prevail, such as the day-month-year order and several Polish language abbreviations.

In Spain, date notation follows the DD/MM/YYYY format. Time notation depends on the level of formality and varies in written and spoken formats. Official time is given using the 24-hour clock, and the 12-hour clock is often used in informal speech.

Date and time notation in Japan has historically followed the Japanese calendar and the nengō system of counting years. At the beginning of the Meiji period, Japan switched to the Gregorian calendar on Wednesday, 1 January 1873, but for much domestic and regional government paperwork, the Japanese year is retained. Japanese people and businesses have also adopted various conventions in accordance with their use of kanji, the widespread use of passenger trains, and other aspects of daily life.

The most formal manner of expressing the full date and/or time in South Korea is to suffix each of the year, month, day, ante/post-meridiem indicator, hour, minute and second with the corresponding unit and separating each with a space:

<span class="mw-page-title-main">Roman timekeeping</span> Hour system with days divided into 24 hours

In Roman timekeeping, a day was divided into periods according to the available technology. Initially, the day was divided into two parts: the ante meridiem and the post meridiem. With the advent of the sundial circa 263 BC, the period of the natural day from sunrise to sunset was divided into twelve hours.

References

  1. 1 2 "Time". The New Encyclopædia Britannica. Vol. 28. 1986. pp. 660 2a.
    "Time". Encyclopædia Britannica. Encyclopædia Britannica Online Library Edition. Retrieved 20 November 2013. The use of AM or PM to designate either noon or midnight can cause ambiguity.(subscription required) For different opinions on representation of midday and midnight, see #Confusion at noon and midnight
  2. 1 2 3 4 "Times of Day FAQs". National Institute of Standards and Technology. 21 September 2016. Archived from the original on 21 September 2018. Retrieved 30 September 2018.
  3. ↑ Addington, Susan (25 August 2016). "Modular Arithmetic". Archived from the original on 4 July 2008. Retrieved 28 November 2008.
  4. ↑ "Is noon 12 am or 12 pm?". Royal Museums Greeenwich. Retrieved 26 January 2023.
  5. ↑ "U.S. Government Printing Office Style Manual - Chapter 12 - Numerals". govinfo.gov. Retrieved 27 January 2023.
  6. ↑ "time of day, elapsed time". Resources of the Language Portal of Canada. 22 October 2020. Retrieved 27 January 2023.
  7. ↑ "The History of Clocks". 13 October 2008. Archived from the original on 13 October 2008. Retrieved 12 November 2017.
  8. ↑ "Berlin instruments of the old Eg.time of day destination". members.aon.at. Archived from the original on 15 November 2006. Retrieved 13 June 2006.
  9. ↑ "Early Clocks". A Walk Through Time. National Institute of Standards and Technology. 12 August 2009.
  10. ↑ National Library of Australia catalogue entry for Rider's British merlin: for the year of Our Lord God 1795. Printed for the Company of Stationers, and sold by R. Horsfield, at Stationers-hall, near Ludgate-street. 1795. Archived from the original on 22 May 2013.
  11. ↑ Lawrence Abrams (13 December 2012). "How to customize how the time is displayed in Windows". Bleeping Computer. Archived from the original on 29 October 2013. Retrieved 26 October 2013.
  12. ↑ "hora". Diccionario panhispánico de dudas (in Spanish). Archived from the original on 20 July 2011.
  13. 1 2 Economist Style Guide (12th ed.). The Economist. 2018. p. 185. ISBN   9781781258316.
  14. ↑ Watson, James Robert. "A more efficient way to denote am or pm". Jim Watson professor of design. Retrieved 30 August 2022.
  15. ↑ Hacker, Diana, A Writer's Reference, six edition, Bedford, St Martin's, Boston, 2007, section M4-c, p.308.
  16. ↑ The Tongue and Quill (PDF). US Air Force. 27 May 2015. p. 356. Archived from the original (PDF) on 26 November 2020. Retrieved 26 October 2021. Air Force Handbook 33-337.
  17. ↑ "quarter". American Heritage Dictionary (3rd ed.). Boston: Houghton Mifflin. 1992. s.v. usage note at end of "quarter" entry.
  18. ↑ Dickens, Charles (1855). Little Dorrit. p. Chapter 27.
  19. ↑ Trudgill, Peter (17 May 2020). "Number five-and-twenty: A fading linguistic practice". The New European. Retrieved 13 October 2022.
  20. ↑ Swan, Michael. "Ask About English". BBC World Service. BBC. Retrieved 13 January 2021.
  21. ↑ "TVTimes magazine 21-27 May 1983 part1". TVTimes. 21–27 May 1983. Archived from the original on 18 October 2012. Retrieved 8 October 2019.
  22. ↑ "United States Government Printing Office Style Manual" (PDF). govinfo. U.S. Government Publishing Office. January 1953. pp. 152, 267. Archived (PDF) from the original on 5 September 2019. Retrieved 5 September 2019.
  23. 1 2 "U.S. Government Printing Office Style Manual" (PDF). govinfo. U.S. Government Publishing Office. 2000. page 156. Archived (PDF) from the original on 5 September 2019. Retrieved 5 September 2019.
  24. 1 2 "U.S. Government Printing Office Style Manual" (PDF). govinfo. U.S. Government Publishing Office. 2008. p. 271. Archived (PDF) from the original on 12 April 2019. Retrieved 5 September 2019.
  25. ↑ 午前１２時？ 午後０時？ [12 AM? or 0 PM?]. National Institute of Information and Communications Technology (in Japanese). 15 February 1989. Archived from the original on 6 June 2017. Retrieved 24 May 2017.
  26. 1 2 質問4-1）正午は午前12時？それとも、午後12時？ [Question 4-1) Is noon 12 a.m.? Or 12 p.m.?]. National Astronomical Observatory of Japan (in Japanese). Retrieved 19 January 2022.
  27. 1 2 Chicago Manual of Style (17th ed.). University of Chicago Press. 2017. paragraph 9.38. ISBN   978-0-226-28705-8. Although noon can be expressed as 12:00 m. (m = meridies), very few use that form.
  28. 1 2 The Canadian Press Stylebook (11th ed.). 1999. page 288.
  29. 1 2 "National Physical Laboratory, FAQ-Time". Archived from the original on 3 March 2015. Retrieved 11 January 2015.
  30. 1 2 Paula Froke, Anna Joe Bratton, Oskar Garcia, Jeff McMillan & Jerry Schwart, Eds., 54th ed., The Associated Press Stylebook and Briefing on Media Law, New York: Basic Books, June 2019, ISBN   978-1-5416-9989-2, s.v. noon, midnight, times.
  31. ↑ "AM". The American Heritage Dictionary of the English Language (Fifth ed.). 2011. Archived from the original on 9 January 2014.
  32. ↑ Richards, E. G. (1999). Mapping Time: the Calendar and its History. Oxford University Press. p. 289.
  33. ↑ "GPO Style Manual. 2016. p.236". govinfo.gov. 12 January 2017. Archived from the original on 17 March 2018. Retrieved 16 March 2018.
  34. ↑ "Cheshunt/Enfield Town to London Liverpool Street via Seven Sisters service Interim train timetables" (PDF). Abellio Greater Anglia London. 17 May 2015. pp. 7, 8. Archived from the original (PDF) on 26 May 2015.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.