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AAT ICAS 2020 ✧ usage guidelines

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.

this document describes normative AAT ICAS usage guidelines documents for ICAS calendar and clock systems.


importance of usage

standards for the expression or representation of units are an important part of the applicable use and the unitary coherence of ICAS. the AAT ICAS usage guidelines documents are intended for use in coordination with other AAT ICAS standards documents, and for use in coordination with other related documents such as standards for usage of SI scales. other standards for particular situations of use or areas of practice may also apply.

issues of usage are more important in situations where measures of different scale are used, and users are responsible for ensuring that any expression of dates and times in ICAS is sufficiently represented for any particular use. certain expressions concerning the use of ICAS or traditional scales of calendar and clock may not be limited in general use to a particular scale (for example, month, monthend, year, yearend, and so forth.), and thus ICAS developers and users should apply ICAS standards or features to promote or ensure the sufficient representation of units for any implementation or application of ICAS. users should observe usage guidelines for the representation and expression of ICAS and traditional scales, and should ensure that the presentation of ICAS documentation conforms to ICAS usage guidelines.

even with practical conditions concerning the sufficient representation of ICAS scales, ICAS terms and formats are designed for concise and practical specification. normative conventions for ICAS usage are referenced herein; however ICAS standards also specify principles of expression that may be regarded as independent of particular formats or localizations. ICAS usage conventions should be regarded as determined by conditions of applicable use. ICAS terms and units are designed for writing or typing without special characters, and are subject to capitalization and lower-casing in support of usable design.


usage defined

matters of usage concern the specification, designation, expression, or representation of ICAS scales by users. usage of term 'specification' in ICAS documentation should however be reserved for the reference or designation of AAT ICAS standards, or for other standards systems. the AAT ICAS usage guidelines documents provide normative guidelines for writing expressions of ICAS scales, and should be used in coordination with other AAT ICAS standards documents.

AAT ICAS usage guidelines are not intended to require the use of any particular format, nor are ICAS specifications for format designed to impose formatting conventions on natural language expression. the purpose of ICAS usage guidelines is to inform the proper use of ICAS. guidelines are under consideration to accommodate usage practices with reference to a wide range of usage guideline resources.

a review of approaches for specifying extensible methods for designating styles or formats for the processing or presentation of date and time expressions remains in process.

although usage guidelines and validation algorithms can inform the development and use of calendar and clock formats, matters of usage are different from matters of algorithms for data validation. thus the specification of methods for validation are beyond the scope of the usage resources documents. please refer to the calculations resources documents at AAT ICAS 2040 for further information.


reference of ICAS standards

please see AAT ICAS 9059 for information about reference of AAT ICAS standards. please see AAT ICAS 9040 for information about licensee use of AAT ICAS standards materials.


representation of ICAS scales

ICAS terms and expressions should be used to represent uses of ICAS scales, methods, and applications. names of ICAS scales or systems are capitalized per a designated ICAS localization, such as AAT ICAS English (AAT ICAS 3100). generally, names of ICAS systems or scales are capitalized as follows: Uniform Calendar, New Calendar, and Inter-Dial Clock.

users may represent ICAS scales with long form terms such as 'Uniform Calendar' or short form terms such as 'UC'. however the short forms of ICAS terms in an application, method, or document should only be expressed if the long forms are already established. in addition, all ICAS scale terms and symbols should only be used unambiguously, and should conform to ICAS usage guidelines (that is, ensure that for any use of ICAS that ICAS or a particular ICAS system is designated).

the use of all caps for even case-structured upper- and lower-cased expressions is sometimes taken as a matter of course. for example, some data-field expressions are formatted as capital characters only. however for expressions that are case-structured for both upper and lower case, the use of both upper and lower case is encouraged to ensure that information cues for case-structured information are not eroded.


usage of metrication expressions

consider the expression of metrication expressions for purposes of ICAS readiness. use the expressions 'International System of Units' or 'SI' to refer to SI. the use of conventional expressions 'metric system' or 'modern metric system' is however discouraged in favor of less ambiguous formulations (for example, SI-1998 or SI-2000). also avoid hyphenating term 'metric' with terms 'SI' or 'ICAS'. consider reserving the use of term 'metric' as an adjective for reference to notions of 'measure' or 'scale' rather than 'system'.

avoid referring to scales or systems of measure in terms of particular communities, organizations, or users unless referring to a specific standard; for example, avoid referring to units as 'american', 'babylonian', 'european', 'imperial', and so forth. metric scales should be referenced in terms of specific systems such as SI or ICAS. traditional scales may be referenced as 'traditional', 'customary', or as 'pre-metric' scales. the proper names of particular units may also be appropriately referenced: for example, 'm k s', '24-hour dial', or 'IFP'.

unless otherwise designated, usage of terms 'SI' or 'ICAS' are to reference a current or effective version. any references to prior versions must be specifically referenced. the status of W3C documents must also be appropriately represented. links to standards documents should be structured to anticipate changes in version or status. consider linking to a high-level directory document to avoid the need to update for lower-level document changes.


other ICAS usage documents

please refer to the following documents for additional usage guidelines:

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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