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AAT ICAS 2200 ✧ guidelines for design of calendar and clock instruments

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.


guidelines for design of ICAS calendar and clock instruments

this document describes AAT ICAS guidelines or best practices for design of ICAS calendar and clock instruments. methods should be documented as appropriate for a particular ICAS application or method. this document is subject to additional specification. please see AAT ICAS 2050 for additional important information.


support for use of multiple scales

developers and users of ICAS methods and applications should consider practicable support for the ready use of multiple scale formats in the design of ICAS calendar and clock instruments. those who design methods or applications (and this includes training) with both ICAS and traditional format capabilities and functions will have an advantage in harnessing benefits and capabilities related to the use of emerging and traditional scale factors.

usable design of ICAS instruments in the context of the use of traditional scales calls for a ready means of conversion to and from traditional scales of calendar and clock by which dates or times may be measured. developers and users will however need to determine appropriate levels of support for the use of multiple scales for any designated method or application.

for example, the expression of an NDN number (and/or JD number) for the last day of a preceding year provides users with a versatile method for the conversion of dates among a number of traditional calendar scales. the use of this method may be further supported by the display of day-of-year numbers and the designation of materials for determining particular conversions, however developers should consider the particular uses for any designated calendar instrument.

similarly, the representation of a secondary scale of time for comparison with a primary scale of time can provide users with a method for determining times among different scales or different time localizations. developers will however need to determine scale formats appropriate for particular uses for any designated clock instrument.


representation of scale conversion

developers and users should consider practicable methods for representing conversion scale values. yet one should first consider the purposes and rationale for accommodating the representation of other scales in a method or application, and should also consider which organization or presentation of material is best suited for a particular method or application.

technical specifications or materials may be best served by the use of a single designated scale of measurement. informative materials may however suitably present a designated primary scale for primary representation, and a parenthetical representation of scale conversions:

system configurations for calendar and clock methods and applications may also be designed for user-selection of time or date scales or formats.


support for use of metric scales

developers should strongly consider incorporating support for the use of metric scales for users as either default settings or as user-selectable configurations. user-selectable scale settings for software should not default to the use of a non-metric scale of measure upon user-selection of a geographic locale that is regarded as non-metric. developers and users should consider that the use of metric scales may be highly practicable for use in new and emerging methods and applications.


design of calendar instruments

developers should consider the presentation of calendar information in support of usable design. formats and layouts should be designed in support of ease-of-use for a designated purpose. the Interform format order is appropriate for tabular or data-centered methods and applications. the prominent display of reference data such as scale, year, and month is useful for user-identification of a calendar instrument. the representation of each Uniform Calendar date in terms of three characters (for example, A01 and A02 instead of 01, 02) is practicable and accommodates a reinforcement of scalar clarity.

one practicable method for displaying both Uniform Calendar and Gregorian calendar dates is by means of a vertical-scale layout for uniform months used in the AAT ICAS all daygroup Uniform Calendars. the AAT ICAS all daygroup Uniform Calendars depict all of the uniform daygroups and the Gregorian weekday daygroup to show how the calendars and daygroups relate; however developers can opt for the display of designated daygroups.

developers and users should consider the practicability of the Uniform Calendar for the processing and reference of calendar dates in terms of design, maintenance, and use. designers should consider the use of design or word-processing software that can accommodate the designation of text-variables for the presentation of years, uniform months, and uniform daygroups.


design of clock instruments

developers and users should consider the usage of decitriad expression for the formal representation of clock times into ordinal groups of three decimal places. most dial unit expressions are however specified for the representation of times for each of the major, minor, and subminor clock units to two numerical places. although the clock units for a dial may be expressed to two numerical places, the normative usage of clock times may be best represented in terms of decitriad expression.

if however a developer or user decides upon a formatted representation of clock units, then the representation should reference a particular dial and the particular clock units. developers and users should moreover consider that the use of a colon as a character delimiter must be restricted to the SMH scale.

except for the dialDecimal configuration, IDC system dial units may be configured to two major clock-digit places and two minor clock-digit places. this is essential for the dialXX, dialXL, and dialL units. the dialHUB configuration may be set to one major clock-digit place yet requires two minor clock-digit places, and the dialPercent configuration requires two major clock-digit places and two minor clock-digit places. any method of decimalization or presentation of decimal places should be clearly represented. instruments for conversion among particular IDC dial-unit configurations should accommodate any of these conditions.

developers should consider the representation of IDC clock instruments in terms of UT and zoneDeka as a primary mode of timesetting, and support for a ready means of scale conversion to and from SMH (however an SMH zoneZodiac-primary instrument may also facilitate a means of IDC conversion/representation if ICAS compliant). please see AAT ICAS 2230 for additional information about timesetting methods.

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


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