Common Calendar
Civil timekeeping demands timestamps with sufficient information to
represent accurate local time. We
present a system called Common Calendar Timestamp System (CCT) that produces
binary and character timestamp formats providing technically accurate and human
readable local time incorporating Coordinated Universal Time (UTC)
leap-seconds, time zones and geographic coordinates.
CCT is organized into layered specifications to provide clear guidance
on the interpretation of International Earth Rotation Reference Systems Service
(IERS) leap-seconds, Internet Assigned Numbers Authority (IANA) Time Zone
Database (Tz Database) information and GIS
coordinates, algorithms for UTC calculation, binary and character timestamp
formats, methods for populating and reading the two formats, and a high-level
Application Programming Interface (API) for convenient manipulation of
calendaring operations.
The binary format is a compound counter composed of [day-number][leap-seconds][time-of-day] with additional local
time metadata to enable efficient machine interchange. The character format is
a human readable form with additional metadata reflecting the information in
the binary format. For example:
D2024-04-11T12:00:00U-04Zamerica/new_yorkAedtV2021aL27S01cMuX
CCT is designed to satisfy people's expectations by representing the
local time as known to the emitting system. The formats are designed to
facilitate calculation of time marks within the current day without need for
access to external metadata. Normalization to UTC is an inherent quality. Geographic coordinate data may be included to
provide traceability provenance for 4D GIS applications.
Central to the CCT implementation is incorporation of the open source Tz Database data and code.
The local time rules in the many time zones all over the world are quite
complex. Tz
Database has undergone years of development to accommodate these intricate
variations and is used directly or indirectly in most operating systems and
timekeeping implementations. CCT now employs its functionality for
interoperation with existing systems such as Linux, Apple and Android. CCT
supports use of Unicode Common Locale Data Repository (CLDR) to map Tz Database time zones to Microsoft Windows time zones.
CCT treatment of UTC is implemented with counting methods to accommodate
the common practice of leap-second introduction in local time simultaneous with
UTC or "rolling leap-seconds" as used by some systems. It also can
accommodate the variations used by NTP and Posix
time. Negative leap-seconds are supported.
Common Calendar Timestamp provides a robust timestamp system for general
purposes and may be implemented with sufficient accuracy to satisfy financial
regulations and be suitable for use as legal time and traceability provenance.
The author hopes the proposal may find support for standardization and looks
forward to the community's suggestions for refinement.
Common
Calendar Specification
UTC Based Local Timescales
Brooks Harris Version 9 2024-04-27
Common Calendar Introduction and Scope
Common Calendar Date and Time Terms and
Definitions
Common
Calendar Local Timescales
Common
Calendar Binary Format (CBF)
Common
Calendar Character Format (CCF)
CCT c/c++ Reference
Implementation