skip navigation, webmaster
ICAS index AAT ICAS Itinica metric resources
previous next

AAT ICAS 1100 ✧ New Calendar (NC) specification

document note: this document is part of the Integrated Chronological Applications System (ICAS). Alliance for the Advancement of Technology (AAT) provides ICAS standards documents subject to terms of use described in document AAT ICAS 9010. please refer to other key AAT ICAS standards documents accessible via the AAT ICAS web site at for important information about ICAS.


general description

New Calendar (NC) methods for the specification of years and days accommodate the use of coherent positive scales for dates throughout the histories of world societies. principles for the use of the New Calendar can be applied to determine factors of calculation among other calendar systems. the NC scale is designated as a principal ICAS era scale.


specification of years corresponding to Gregorian calendar

a New Calendar system era is derived from the Gregorian calendar via the correspondence of NC 12000 to AD 2000. Gregorian calendar years may thus be converted to NC-era calendar years by adding 10 000. the system identifier term 'NC' may be used to designate the use of the New Calendar for a date in the NC era.


specification of years corresponding to Julian calendar

New Calendar dating of years corresponding to the Julian calendar, precursor of the Gregorian calendar, is subject to the different scales used for various years in different regions. transitions from the Julian calendar to the Gregorian calendar recalculated the formula used for determining leap years, introduced a tropical calendar correction, and applied a change in the beginning of a new year from March 25 to January 01. these transitions occurred in different regions from AD 1582 to 1923. the Julian calendar was introduced in AUC 709 (BC 45), the Julian AD scale was established in AD 532, and the BC scale was described in AD 722. a year zero was not designated between the AD and BC scales, and thus BC-era years may be approximated to NC-era years by subtracting from 10 001. however this method of dating for dates subject to the Julian calendar is based on conformance with the Gregorian calendar upon which the New Calendar is derived, and additional calculation factors may apply.

calendar rules are sometimes specified in terms of ecclesiastical or civil objectives. the objective of ICAS is to specify methods by which various calendar rules may be accommodated in terms of ICAS.


specification of New Calendar leap years

determination of a leap year in the New Calendar system is derived from the Gregorian calendar system. leap years are based on the correspondence of NC 12000 and AD 2000, and extend retroactively for all New Calendar dates. leap years are all years that are divisible by 4 with no remainder except for years that are divisible by 100 with no remainder, of which only those years divisible by 400 with no remainder are leap years.

moreover, year NC 00000 and the year 0 of any NC pre-scale is also a leap year. NC pre-scales must conform to the same numerical formula for the determination of leap years as the NC scale, and must further determine leap years consistently for years common to both scales.


specification of New Calendar pre-scale eras

years occurring before the NC scale are for normative expressions to be expressed in terms of coherent positive numbers via the designation of a coherent NC pre-scale. a pre-scale may be specified in terms of a system of uniform yeargroups specified in table 1100.2. a pre-teralennial scale is specified as the quantifiable subset of the teralennium of main units immediately preceding the current NC teralennium as specified table 1100.1 ✧ specification of pre-teralennial scale.


table 1100.1 ✧ specification of pre-teralennial scale

preTium 0-999-999-000-000preMium 000-000
preTium 0-999-999-999-999preMium 999-999
preTium 1-000-000-000-000NC 00000
preTium 1-000-000-000-001NC 00001
preTium 1-000-000-012-004NC 12004


specification of uniform yeargroups

uniform yeargroups are yeargroups such as a decade, century, or millennium that in a primary sense are fixed coherent to yeargroup sequences in relation to year NC 00000 of the New Calendar. AAT ICAS uniform yeargroups are listed in table 1100.2 ✧ uniform yeargroups for New Calendar years, and are subject to term set localization.

by definition, the uniform yeargroup megalennium (Mium) is equal to 365 242 500 main units (NC-era days) in a uniform yeargroup of 1 000 000 New Calendar years. the larger uniform yeargroups do not necessarily correspond to the number of terrestrial days in these periods, due to gradual changes in the duration of the Earth's rotation. nonetheless, in addition to the use of metric prefix multiples of the IDC main unit (as in AAT ICAS 3130), the larger uniform yeargroups provide another method for conceptualizing larger scales of time in terms of calendar units defined in terms of the IDC main unit (AAT ICAS 1300).

special note: the IDC main unit is decimally coherent to a main unit of one day, and a fixed implementation is linked precisely to the SI second. although uniform yeargroups are linked precisely to the IDC main unit, they are not decimally coherent to the main unit. care should thus be exercised in the usage of uniform yeargroup scales as calendrical or timeline scales to avoid confusion with main unit scales of time as clock scales.


table 1100.2 ✧ uniform yeargroups for New Calendar years

annum1* coordinated, not fixed
biennium2* coordinated, not fixed
decadedium10* coordinated, not fixed
centuryhium100* coordinated, not fixed
millenniumkium1000* coordinated, not fixed
tenmillenniumten-kium10 000
hundredmillenniumhun-kium100 000
megalenniumMium1 000 000365 242 500 main units
tenmegalenniumtenMium10 000 000
hundredmegalenniumhunMium100 000 000
gigalenniumGium1 000 000 000
tengigalenniumtenGium10 000 000 000
hundredgigalenniumhunGium100 000 000 000
teralenniumTium1 000 000 000 000

uniform yeargroups may further be designated in terms of localized term sets subject to AAT ICAS 1400. please see the AAT cosmological timeline (AAT ICAS 2036) for additional information about uniform yeargroups.


specification of day notation for New Calendar era

a system of New Calendar Day Notation (NDN) is derived from the New Calendar scale of years, and is counted from the first day of year NC 00000 at IDC t000 deka(0). please refer to the AAT ICAS Inter-Dial Clock (IDC) system specification (AAT ICAS 1300) for additional information about IDC.

UCN 12000A01 at IDC t250 deka(0) may be specified in day notation as NDN 4382912.25 or as NDN 4382912t250.

methods in the dating of years, months, and days throughout history are numerous; and NDN dating of dates subject to other and earlier scales of year, month, and day may call for the consideration of additional conversion factors. please see AAT ICAS 2040.


specification of day notation for pre-scale eras

methods for the normative designation of NC pre-scales shall also accommodate the use of coherent positive scales for day notation of day dates occurring before a principal era. day notation for days in the pre-teralennial era may be designated in the same terms used for years. for example, the specification preMium-DN designates a scale fixed from the first day of the pre-megalennial scale beginning one million years before the New Calendar era (preMium 000-000), as per table 1100.2-specification of pre-teralennial scale.


table 1100.3 ✧ day notation values in the pre-megalennial scale preMium-DN

(non-normative region of NDN scale)preMium-DN 365242500
NDN 0preMium-DN 365242501
NDN 1preMium-DN 365242502

top document updated:

system identifiersdatetime
Uniform CalendarUCUCN 12019 S19 Yellow
Inter-Dial ClockIDCzone(UT)t339 tt050
'ICAS in use' can accommodate calendar and clock formatting 'for all people, for all time'.
day of yearD-o-YAD common year day139
Gregorian calendarGG2019 May 19 Sunday
seconds, minutes, hoursSMHUT08:08:14
style legend


contents of this web site copyright © 2019 UCA and prior, Alliance for the Advancement of Technology.
mission, terms of use, privacy, e quality guarantee, search, contact AAT.
Valid XHTML 1.1!ICAS in use level AICAS in use level Be quality guarantee