Standard No.:	GB/T 7408.1-2023
English Name:	Date and time—Representations for information interchange—Part 1: Basic rules
Chinese Name:	日期和时间 信息交换表示法 第1部分：基本原则
Professional Classification:	GB    National Standard
Issued on:	2023-12-28
Implemented on:	2024-4-1
Status:	valid
Superseding:	GB/T 7408-2005 Data elements and interchange formats—Information interchange—Representation of dates and times
Target Language:	English
File Format:	PDF
Word Count:	20000 words
Translation Price(USD):	600.0
Delivery:	via email in 1~3 business day

GB/T 7408.1-2023 Date and time - Representations for information interchange - Part 1: Basic rules 1 Scope This document specifies representations of dates of the Gregorian calendar and times based on the 24‑hour clock. This document applies to the representation of dates and times in information exchange. It is also applicable for representing times and time shifts based on Coordinated Universal Time (UTC). This document excludes the representation of date elements from non‑Gregorian calendars or times not from the 24‑hour clock. This document does not address character encoding of representations specified in this document. 2 Normative references There are no normative references in this document. 3 Terms, definitions and symbols 3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1.1 Basic concepts 3.1.1.1 date time on the calendar time scale Note: Common forms of date include calendar date, ordinal date or week date. 3.1.1.2 time mark attributed to an instant or a time interval on a specified time scale Note 1: The term “time” is often used in common language. However, it should only be used if the meaning is clearly visible from the context. Note 2: On a time scale consisting of successive time intervals, such as a clock or calendar, distinct instants may be expressed by the same time. Note 3: This definition corresponds with the definition of the term “date” in IEC 60050‑113:2011, 113‑01‑12. 3.1.1.3 instant point on the time axis Note: An instantaneous event occurs at a specific instant. [SOURCE: IEC 60050‑113:2011, 113‑01‑08] 3.1.1.4 time axis mathematical representation of the succession in time according to the space‑time model of instantaneous events along a unique axis Note 1: According to the theory of special relativity, the time axis depends on the choice of a spatial reference frame. Note 2: In GB/T 2900.93-2015, 113-01-03, time according to the space-time model is defined to be the one‑dimensional subspace of space‑time, locally orthogonal to space. [SOURCE: IEC 60050-113:2011, 113-01-07, modified] 3.1.1.5 time scale system of ordered marks which can be attributed to instants on the time axis, one instant being chosen as the origin Note: A time scale may amongst others be chosen as: ——continuous, e.g. international atomic time (TAI) (see GB/T 2900.54-2002, 713-05-18); ——continuous with discontinuities, e.g. UTC due to leap seconds, standard time due to summer time and winter time; ——successive steps, e.g. calendars, where the time axis is split up into a succession of consecutive time intervals and the same mark is attributed to all instants of each time interval; ——discrete, e.g. in digital techniques. [SOURCE: IEC 60050-113:2011, 113-01-11, modified] 3.1.1.6 time interval part of the time axis limited by two instants and, unless otherwise stated, the limiting instants themselves [SOURCE: IEC 60050-113:2011, 113-01-10, modified] 3.1.1.7 time scale unit unit of measurement of a duration Example 1: Calendar year, calendar month and calendar day are time scale units of the Gregorian calendar. Example 2: Clock hour, clock minutes and clock seconds are time scale units of the 24‑hour clock. 3.1.1.8 duration non-negative quantity of time equal to the difference between the final and initial instants of a time interval Note 1: The duration is one of the base quantities in the International System of Quantities (ISQ) on which the International System of Units (SI) is based. The term “time” instead of “duration” is often used in this context and also for an infinitesimal duration. Note 2: For the term “duration”, expressions such as “time” or “time interval” are often used, but the term “time” is not recommended in this sense and the term “time interval” is deprecated in this sense to avoid confusion with the concept of “time interval”. Note 3: The exact duration of a time scale unit depends on the time scale used. For example, the durations of a year, month, week, day, hour or minute, may depend on when they occur [in a Gregorian calendar, a calendar month can have a duration of 28, 29, 30, or 31 days; in a 24-hour clock, a clock minute can have a duration of 59, 60, or 61 seconds, etc.]. Therefore, the exact duration can only be evaluated if the exact duration of each is known. Note 4: This definition is closely related to NOTE 1 of the terminological entry “duration” in IEC 60050‑113:2011, 113‑01‑13. 3.1.1.9 clock time scale suited for intra‑day time measurements Example 1: The 24-hour clock is a type of clock. Example 2: clock second, clock minute and clock hour are often time scale units included in a clock. 3.1.1.10 24-hour clock clock that subdivides a calendar day into 24 clock hours Note: UTC forms the basis of today’s 24‑hour clocks and is used in this document as a type of 24‑hour clock, as described in 4.2.3. 3.1.1.11 recurring time interval series of consecutive time intervals of identical duration Note: If the duration of the time intervals is measured in calendar entities, the duration of each time interval depends on the calendar dates of its start and end. 3.1.1.12 Coordinated Universal Time UTC time scale with the same rate as International Atomic Time (TAI), but differing from TAI only by an integral number of seconds Note 1: UTC is the time standard commonly used across the world from which local time is derived. Note 2: UTC is produced by the Bureau International des Poids et Mesures (BIPM), i.e. the International Bureau of Weights and Measures. Note 3: TAI is a continuous time scale produced by the BIPM based on the best realizations of the SI second. TAI is a realization of Terrestrial Time (TT) with the same rate as that of TT, as defined by the International Astronomical Union Resolution B1.9 (2000). [SOURCE: BIPM Recommendation CCTF 3 (2017), modified] 3.1.1.13 UTC of day time of day in UTC 3.1.1.14 standard time time scale derived from UTC, by a time shift established in a given location by the competent authority Example 1: Some standard times do not vary within a year, such as US Eastern Standard Time (EST), US Eastern Daylight Time (EDT), Australia Western Standard Time (AWST), China Standard Time (CST), Hong Kong Standard Time (HKT), Korea Standard Time (KST) and Japanese Standard Time (JST). Example 2: Some standard times vary within a year, such as US Eastern Time (ET) and Australian Central Standard Time (ACST). Note: The time shift of a standard time may vary in the course of a year, such as due to daylight savings. [SOURCE: IEC 60050-113:2011, 113-01-17, modified] 3.1.1.15 local time scale locally‑applicable time scale such as standard time or a non‑UTC based time scale 3.1.1.16 time of day time occurring within a calendar day Note 1: Generally, time of day relates to the duration elapsed after the beginning of the day. However, this correlation breaks when changes occur in the time scale that applies to the time of day, such as time shifts and leap seconds. Note 2: This definition corresponds closely with the definition of “clock time” given in IEC 60050‑113:2011, 113-01-18, except that the concepts of duration and time scale are not used in this definition. 3.1.1.17 local time of day time of day (3.1.1.16) in a local time scale 3.1.1.18 calendar time scale that uses the time scale unit of calendar day as its basic unit Example: The Gregorian calendar is a type of calendar. Note: calendar month and calendar year are time scale units often included in a calendar. 3.1.1.19 Gregorian calendar calendar in general use that defines a calendar year that closely approximates the tropical year Note: In this document the term “Gregorian calendar” is used to refer to the time scale described in 4.2.1.