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Decimal
Time:
Decimal Time - Proposals
This page examines various proposals for representating the time of day. Decimal time of day proposals divide the day by powers of ten, e.g. 1/10, 1/100, 1/1000, etc., which can be easily converted into a decimal fraction of the day. Other proposals do not divide the day decimally, but represent time of day as decimal fractions of other bases, such as 1/15, 1/20, 1/24, 1/25, 1/40, etc.
Dividing the Day
A comparison of proposals, including base units and subunits, the start of the day in relation to Universal Time (GMT), and the characters used to separate subunits.
| Name | Base Unit | Second Unit | Third Unit | UT offset | Separator | |||
|---|---|---|---|---|---|---|---|---|
| ISO 8601 | 1 | day | local | . or , | ||||
| MY.NT | 10 | NH | 10 | NM | 10 | NS | local+6h | : |
| Orlantia | 10 | watches | 10 | zons | 10 | breaths | ||
| Tentime | 10 | decimi | 10 | centimi | 10 | millimi | local+6h | . |
| FRT | 10 | hours | 100 | minutes | 100 | seconds | +9.35m | : |
| NDST | 10 | hours | 100 | minutes | 100 | seconds | 0 | : |
| DC | 10 | Aitus | 100 | HectAitus | 100 | MyriAitus | 0 | . |
| MTC | 15 | metric hours | 100 | metric minutes | 100 | metric seconds | ? | |
| 20h #1 | 20 | hours | 100 | minutes | 20 | seconds | local | : |
| 20h #2 | 20 | hours | 100 | minutes | 100 | seconds | local | : |
| Flow | 24 | hours | 100 | minutes | 100 | seconds | local | : |
| 25h | 25 | hours | 100 | minutes | 100 | seconds | local | : |
| GM<m>T | 40 | hours | 1000 | millihours | 0 | . | ||
| ASMT | 40 | demurs | 1000 | hesits | local | . | ||
| Kermetric | 100 | Kermits | local | . | ||||
| ADT | 100 | aristos | 10 | deciars | 100 | milliars | local+18h | . or : |
| China | 100 | tshei | 100 | ke | ||||
| Wt | 100 | measures | 100 | beats | +12h | . | ||
| PMT | 100 | hours | 100 | minutes | 100 | seconds | 0/local | . |
| UMT | 100 | cents | 1000 | quints | +12h | . | ||
| LMT | 100 | cents | 1000 | quints | local | . | ||
| GST | 100 | kt | 1000 | ticks | +12h | , | ||
| RMT | 100 | R-hours | 1000 | R-millihours | 1000 | R-microhours | 0 | . |
| IT | 1000 | beats | +1h | @ | ||||
| @Time | 1000 | beats | 100 | centibeats | +1h | @ . | ||
| Chrons | 1000 | chrons | 100 | centichrons | 0/local | . | ||
| Udt | 1000 | t | 1000 | milli t | 0 | -,. | ||
| DT | 1000 | tims | 1000 | millitims | 1000 | microtims | 0 | . |
| Unix | 86,400 | seconds | 1000 | millisecnds | 0 | . | ||
| XTime | 100,000 | chi | +12h | |||||
| TSD | 1,000,000 | sekants | 0 | |||||
One per Day
The following is a proposed change to Section 5.3.1.3 of International Standard ISO 8601: Representation of dates and times to include the representation of a decimal fraction of the day. Inserted text is blue. As explained therein, commas are used for the decimal sign in the text, instead of decimal points, in deference to other countries, but example "d" could also be represented as 1985-04-12.1, for instance, or 1985-04-12.100.
5.3.1.3 Representation of decimal fractions
If necessary for a particular application a decimal fraction of day, hour, minute or second may be included. If a decimal fraction is included, lower order components (if any) shall be omitted and the decimal fraction shall be divided from the integer part by the decimal sign specified in ISO 31-0: i.e. the comma [,] or full stop [.]. Of these, the comma is the preferred sign. If the magnitude of the number is less than unity, the decimal sign shall be preceded by two zeros in accordance with 4.8. The number of digits in the decimal fraction shall be determined by the interchange parties, dependent upon the application. The format shall be [hhmmss,ss], [hhmm,mm], [hh,hh] or [DD,DD] as appropriate (hour minute second, hour minute, hour and day, respectively), with as many digits as necessary following the decimal sign. A decimal fraction shall have at least one digit. In the examples below it has been agreed to expand the smallest time element with one digit.
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Ten per Day
Most decimal time proposals replicate French Revolutionary Time by dividing the day into 10 hours,
each hour into 100 decimal minutes, and each decimal minute into 100 decimal seconds, making for 100,000 decimal seconds per day.
This decimal second is slightly shorter than the SI second, while the decimal minute slightly is longer than a standard minute,
and the decimal hour is 2.4 standard hours long.
Malaysian New Time
Ling Lay Pee & Simon Loh propose "Malaysian New Time" (MY.NewTime), with a "new day" (ND), beginning at 6:00 am local time, of 10 "new hours" (NH), each new hour with 10 "new minutes" (NM), each new minute with 10 "new seconds" (NS). A so-called "new second" is 86.4 SI seconds, and more precise time is represented by "new milliseconds" (NmS). Also proposed are 10 local time zones, each 36 degress wide.
James L.R. Beach has devised a role-playing game with its own decimal time and calendar for a fictional planet named Orlantia. The day is divided in to 10 watches, which are divided in to 10 zons, which are divided into 10 breaths, whic are divided into 10 bits, which are divided into 10 beats. This planet also has two moons which have orbital periods of 10 and 20 days, respectively called Folars and Septers, while the year is exactly 400 days long, divided into 4 seaons of 100 days each.
Tentime is both a calendar and time-keeping system. The day starts at 6:00 AM local time, and the year starts on the vernal equinox. A year consists of 36 ten-day weeks, plus a partial week of five or six days. Dates are represented either in ordinal YYYY-DDD format, or with special week and day names. Days are divided into ten "decimi" (singular "decimus"), one hundred "centimi," one thousand "millimi," ten thousand "eximi," and one hundred thousand "proximi."
Deci-Time has the usual 10 hours per day, 100 minutes per hour 100 seconds per minute, along with a calendar in which there are five days per week, five weeks per month, fifteen months per year, with the last month deficient with only three weeks.
Fifteen per Day
Peter Hansen and Peder Hansen (no relation) invented a Metric Time Concept which divides the "metric day" into 15 "metric hours" of 100 "metric minutes" of 100 "metric seconds." Also, 10 "metric days" is a "metric week," 3 of which make 1 "metric month," 10 of which make 1 "metric year."
Twenty per Day
Bill Collins has devised a system which divides the day into 20 hours, each hour into 100 minutes and each minute into 100 seconds. (An earlier proposal divided each minute into 20 seconds.) The reason for using 20 hours is that it is closer to the currently used 24 hours. The range of times is 00:00:00 to 19:99:99, although his analog clocks show 20. He also proposes revising the time zones so that there are 20, instead of 24.
Twenty-four per Day
Decimal hours are sometimes called "decimal time," even though they are based upon a non-decimal division of the day. Decimal hours represent the whole number of hours of day, and minutes and seconds as decimal fractions of hours. For instance, 12 o'clock is 12.0 and 12:30 is 12.5. No attempt has been made use metric multiples and submultiples with decimal hours. These are sometimes used with employee time clocks. Jesse Yoder's Flowtime proposes dividing hours into 100 decimal minutes, each minute being 36 SI seconds long, but divided into 100 decimal seconds, each 0.36 SI seconds long.
Twenty-five per Day
J. William Cupp proposes a "Metric Day," which divides the day into 25 hours, each hour into 100 minutes and each minute into 100 seconds. The range of times is 00:00:00 to 24:99:99, or 12 hours a.m. and 13 hours p.m. There are also three proposals for a "Metric Year", although they are not decimal-based.
Forty per Day
An early metric unit which is still occassionally used, although it is not part of SI, is the grad or grade, which is a unit of angular measure equal to 1/100 of a right angle, resulting in 400 grads in a complete circle. Likewise, the metre was originally defined as 1/10,000,000 the distance from the equator to the North Pole, making about 40,000 kilometres for the complete circumference of the earth. Viewing a clock or the apparent path of the sun as a circle, this has inspired some to decimally divide quarter days, instead of whole days. K.E.V. Palmen has proposed using the grad, itself, as a unit of time, dividing the day into quarters of 100 grads each.Bob Ragot and Grand Admiral Petry both divide the day into 40 parts. The circular analog clock, which is a representation of the earth's rotation, is divided into quadrants, each of which are divided in 10 parts. The range of times is 00.000 to 39.999. Petry calls his 1/40 day unit a "demur", and each thousandth of a demur a "hesit". Ragot calls his 1/40 day unit an "hour" with decimal fractions which could be represented with metric prefixes.
Meck time is based on the fact that the metre was originally defined to be 1/40,000,000 of the circumference of the earth. Therefore, the base unit of "metric time" is defined as 1/40,000,000 day, which is named a "tick", equal to 2.16 milliseconds, and multiples and submultiples formed by adding metric prefixes, although these are given nicknames, e.g. "Meck" for "megatick", "Click" for "kilotick", "Nick" for "nanotick", and "Helic" for "hectokilotick" (although the latter does not use an accepted metric prefix). Time of day is determined by dividing the day into four quadrants of 10 Mecks (6 hours) each, with "Morning" lasting from 0.00-9.99 (3-9am), "Day" from 10.00-19.99 (9am-3pm), "Evening" from 20.00-29.99 (3-9pm), and "Night" lasting from 30.00-39.99 (9pm-3am). Midnight is at 35.00 and noon at 15.00, so the calendar date begins and ends with 00.00 at 3 am local standard time.
One Hundred per Day
Lyle Zapato's Universal Metric Time (UMT), like GST,
begins and ends at midnight at the International Date Line. (IDL) However, he also specifies Local Metric Time (LMT), which is
adjusted to the currently recognized local time zones. The range of times are 00.000 to 99.999.
Percentage Metric Time
Ray L. Winstead of Indiana University of Pennsylvania has written a Percentage Metric Time Clock, dividing the day into 100 Percentage Metric Hours, each divided in to 100 Percentage Metric Minutes, themselves divided into 100 Percentage Metric Seconds. There are one million PMS per day. He defines both local PMT based on current time zones and World Standard PMT based on UTC.
jonathan jay has developed three versions of his Global Standard Time, all of which begin and end at midnight on the International Date Line, or UT+1200, and do not use any local time or time zones.
- WRLD.time divides the day into one hundred "measures", each of which is
divided into one hundred "beats", separated by a decimal point. Each measure is 14.4 minutes, and each beat is 8.64
seconds. The range of times is 00.00 to 99.99.
- XTime: see below.
- Global Standard Time 3.0 extends the second division by a third digit. The range is 00.000 to 99.999. The base unit is called a "tick" (t), which is 1/100,000 of a day, or 0.864 seconds. The larger unit is a "kilotick" (kt), which is 14.4 minutes.
Aristeo Canlas Fernando divides the day into 100 "aristos" (ar or A), which are divided into 10 "deciaristos" or "deciars" (dar or dA) and 1000 "milliaristos" or "milliars" (mar or mA). The aristos and deciars may be separated by either a decimal point (.) or colon (:), but the decimal point requires use of the unit abbreviation, while the colon does not. The most distinguishing feature of ADT is that its days begin and end with 0:000 (0.0ar) at 6:00 p.m. standard time, similar to Jewish practice.
One Thousand per Day
Universal Date & Time
The now-defunct Universal Time Organisation promoted what they called Universal Date & Time
(Udt) which combined ISO 8601 date formats (including calendar dates, ordinal dates and week dates) with decimal time units of
0.001 day, called "t", seperated from the date by a comma and optionally including a decimal fraction. For example,
U2004-309,282.926 = U2004-W44-4,282.926 = U2004-11-04,282.926.
Chrons
Seth Golub divides the day into 1000 "chrons". He further defines 10 "decichrons"
and 100 "centichrons" per "chron". Range of times are 000.00c to 999.99c. He is ambiguous about whether they should be
synchronized with UTC or local standard time.
Decimal Time Society
The Decimal Time Society, which was apparently a person named Michael Pinder, called his decimal time proposal, "Decimal Time". The epoch is at midnight UTC before the last vernal equinox of the 20th century, i.e. March 20, 2000 CE. The first three digits specify the year, starting with 000, followed by a colon (:), then three digits for the number of days since the vernal equinox, starting with 000, and a decimal point followed by the decimal fraction of the day, to at least three more digits. The base unit is 0.001 day and called a "tim", which may also be divided into "millitims", "microtims", etc. The calendar displays a ten-day week, with both 9 40-day and 12 36-day months, plus five "dog days". All times are based on UTC, from .000 to .999.
86,400 per Day
Space Oddity
Space Oddity creator Gary Davidson created a "Metric Time" based on the SI second of 1/86400 day for use on this program, inspired by Star Trek's stardates. The base unit is the Metric Day (MD), equal to 100,000 seconds, or 27.78 hours. He further defined metric hours, minutes and seconds as 0.10000, 0.00100 and 0.00001 MD, respectively, and metric weeks, cycles and years as 10, 100 and 1000 MD, respectively. None of these units relate to standard units, except for the Metric Second. Time is counted by the number of seconds from 12:15 p.m. Greenwich Daylight Savings time, April 9, 1964, divided by 100,000, which is is expressed as 00000.00000.
One Hundred Thousand per Day
XTime
XTime like GST, begins and ends at midnight on the International Date Line, or UT+12 (GMAT), and does not use any local time or time zones. The range is 00000 to 99999. The base unit is a "chi" (χ), which is 10-5 of a day. Chi is the initial letter of the Greek word for time, chronos (χρονος). Dates are represented by the cardinal number of days in the year, with January 1 as 0. [0-365]
One Million per Day
Tempus Spatium Dates
Dorian Aescher proposes a base unit of 1/1000000 day, or 0.0864 seconds, called a "sekant," from the Latin "to cut." It would have the symbol (S) and replace the SI second as the base unit for derived metric measures, using metric multiples for longer periods. Clocks would display time in 000-999 kilosekants or 000 000-999 999 sekants, with "000 000 GST" (Global Standard Time) being 00:00 GMT. He also proposes a 1000-day "linear" calendar, which which displays an integer date with the epoch being the launch of Sputnik on 4 October, 1957, and the days of the year being notated by an integer beginning at the vernal equinox. He further proposes replacing the 7-day work week with a 10-day period containing days with names derived from their numerical order, and replacing the entire SI metric system with all new base units and prefixes.
One Billion per Year
GigaTicks
Richard Ortiz divides one tropical year into one billion "Ticks". Time is based solely upon decimal divisions of a year, redefining the definitions of other units, including the day. One "Tick" equals 0.0315569 seconds, one "KiloTick" lasts for 31.55 seconds, one "MegaTick" is 8.77 hours, one "GigaTick" is exactly one year, or 365.2422 days, and one "TeraTick" is one millenium. Absolute metric time is defined as beginning on noon, 12 June, year 0 (1 BCE), measured in "Ticks", i.e. billions of a year. He also has a metric calendar, dividing the year into ten months, beginning with January 0 on the summer solstice, with the same month-names, except for July and August. Each month is divided into 10 weeks, which are divided into 10 "days", named after the sun and nine planets, in reverse order from the sun. These "days" are 8.77 hours, or about one work shift.