ANSI INCITS 310-1998 Information Technology - Representation of Time for Information Interchange.pdf

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1、ANSI INCITS 310-1998 (R2003)(formerly ANSI NCITS 310-1998)for Information Technology Representation of Timefor Information InterchangeANSINCITS 310-1998Revision, redesignation, and consolidation ofANSI X3.43-1991 and ANSI X3.51-1994American National Standardfor Information Technology Representation

2、of Timefor Information InterchangeSecretariatInformation Technology Industry Council (ITI)Approved February 23, 1998American National Standards Institute, Inc.Approval of an American National Standard requires review by ANSI that therequirements for due process, consensus, and other criteria for app

3、roval havebeen met by the standards developer.Consensus is established when, in the judgement of the ANSI Board ofStandards Review, substantial agreement has been reached by directly andmaterially affected interests. Substantial agreement means much more thana simple majority, but not necessarily un

4、animity. Consensus requires that allviews and objections be considered, and that a concerted effort be madetowards their resolution.The use of American National Standards is completely voluntary; theirexistence does not in any respect preclude anyone, whether he has approvedthe standards or not, fro

5、m manufacturing, marketing, purchasing, or usingproducts, processes, or procedures not conforming to the standards.The American National Standards Institute does not develop standards andwill in no circumstances give an interpretation of any American NationalStandard. Moreover, no person shall have

6、the right or authority to issue aninterpretation of an American National Standard in the name of the AmericanNational Standards Institute. Requests for interpretations should beaddressed to the secretariat or sponsor whose name appears on the titlepage of this standard.CAUTION NOTICE: This American

7、National Standard may be revised orwithdrawn at any time. The procedures of the American National StandardsInstitute require that action be taken periodically to reaffirm, revise, orwithdraw this standard. Purchasers of American National Standards mayreceive current information on all standards by c

8、alling or writing the AmericanNational Standards Institute.American National StandardPublished byAmerican National Standards Institute, Inc.11 West 42nd Street, New York, NY 10036Copyright 1998 by Information Technology Industry Council (ITI)All rights reserved.No part of this publication may be rep

9、roduced in anyform, in an electronic retrieval system or otherwise,without prior written permission of ITI, 1250 Eye Street NW, Washington, DC 20005. Printed in the United States of AmericaiContentsPageForeword ii1 Scope, purpose, and application 12 Definitions. 13 Specificiations. 24 Combinations o

10、f date and time representation. 4AnnexesA Relationships between representations of time for information interchange,Daylight Saving Time, and U.S. Time Zone code sets . 5B Explanation of designation civil time. 8C Sources of time information 9D Bibliography 11iiForeword (This foreword is not part of

11、 American National Standard NCITS 310-1998.)This standard provides a single, unambiguous format for representing time in infor-mation interchange. Time refers to an instant in the time continuum of a day. Thebasic representation of time for information interchange specified in this standard isHHMMSS

12、.ssss plus a time-differential from coordinated universal time, where HHrefers to the hour in the twenty-four-hour time-keeping system, MM refers to theminute, SS refers to the second, and ssss refers to the decimal second (to whatev-er number of significant digits may be necessary). This standard w

13、ill be of interest toinformation and data managers, data administrators, and others responsible for mak-ing data sharable. It will also be of interest to manufacturers of repository and CASEtool products.This standard addresses the need for a single standard for information interchange oftime data.

14、It combines two previous American National Standards on time in orderto reduce potential confusion possible with two separate standards relating to time.A single standard for representation of time that incorporates all relevant aspects ofthe representation of time is desirable in order to reduce po

15、tential confusion in inter-change of time information. Other standards for representing time in information in-terchanges contain various options for interchange of time; thus, potential confusioncan arise as to the exact format being used for interchange of time. This standardeliminates such potent

16、ial confusion.This standard was developed within the usual consensus process of ANSI standardscommittees. Knowledgeable experts from the U.S. Naval Observatory, the NationalInstitute for Standards and Technology, Lawrence Berkeley Laboratory, and other or-ganizations participated in the development

17、of this standard. Issues were fully dis-cussed, with pros and cons identified, and votes taken to resolve them.This standard contains four annexes, Annex A is normative and is considered part ofthis standard. The remaining annexes are informative and are not considered part ofthe text.Requests for i

18、nterpretation, suggestions for improvement or addenda, or defect re-ports are welcome. They should be sent to the National Committee for InformationTechnology Standards (NCITS), ITI, 1250 Eye Street, NW, Suite 200, Washington,DC 20005.This standard was processed and approved for submittal to ANSI by

19、 NCITS. Com-mittee approval of this standard does not necessarily imply that all committee mem-bers voted for its approval. At the time it approved this standard, NCITS had thefollowing members:Karen Higginbottom, NCITS Chair (Acting)Karen Higginbottom, NCITS Vice-ChairMonica Vago, NCITS SecretaryOr

20、ganization Represented Name of RepresentativeAMP, Inc. John HillCharles Brill (Alt.)Apple Computer, Inc. David K. Michael Jerry Kellenbenz (Alt.)AT it does not describe how time is determined. This standard was not designed for(nor does it preclude) usage by humans as input to, or output from, data

21、systems.1.2 PurposeThe purpose of this American National Standard is to provide a single, unambiguous standard means ofrepresenting time for interchange of time information among data systems.1.3 ApplicationThe representation of time specified in this standard is compatible with other national and i

22、nternationalstandards. The representation specified by this American National Standard is in the basic format of“differences between civil time and Coordinated Universal Time” (as described in ISO 8601:1988), with anextension to represent designated civil time, which is defined to have the same nume

23、rical representationacross all time zones.1.4 CancellationsThis standard cancels and replaces American National Standard for Information SystemsRepresentations of Local Time of Day for Information Interchange (ANSI X3.43-1991) and AmericanNational Standard for Information Systems Representations of

24、Universal Time, Local Time Differentials,and United States Time Zone References for Information Interchange (ANSI X3.51-1994).2 DefinitionsFor this American National Standard, the following definitions apply:2.1 time: “In English time is used to specify an instant (time of day)” ITU-R Recommendation

25、s, 1994TF Series Volume, Time Signals and Frequency Standards Emissions (Recommendation 686, Glossary).A particular point in the stream of time at a particular place (which may or may not be specified in terms ofa particular date): A specific hour, or minute, or second, or fraction of a second in a

26、day at a specificplace.2.2 second: “The duration of 9 192 631 770 periods of the radiation corresponding to the transitionbetween the two hyperfine levels of the ground state of the cesium atom-133.” (XIIIeConference Generaledes Poids et Mesures, 1967). Ordinarily, a second is one-sixtieth of a minu

27、te.2.3 leap second: A second of time intentionally inserted in or deleted from the UTC time stream to keepit approximately compatible with the rotation of the Earth. An inserted second is called a positive leapsecond and an omitted second is called a negative leap second. For the purposes of this st

28、andard, aANSI NCITS 310-19982positive leap second is labeled “60” and a negative leap second is labeled “58” (there being no secondwith the label “59” in a minute with a negative leap second).2.4 minute: Sixty seconds, each labeled consecutively in the 24-hour timekeeping system from 0 through59 beg

29、inning with the start of the first second after the beginning of the minute. Ordinarily, a minute isone-sixtieth of an hour.NOTE: A minute that contains a leap second will have 61 or 59 seconds, depending upon whether the leapsecond is positive or negative, respectively.2.5 hour: Sixty minutes, each

30、 labeled consecutively in the 24-hour timekeeping system from 0 through 23beginning with the start of the first minute after the beginning of the hour. Ordinarily, an hour is onetwenty-fourth of a day.NOTE: An hour that contains a leap second will have one extra or one less second, depending uponwhe

31、ther the leap second is positive or negative, respectively.2.6 date: A particular day within a Gregorian calendar month, consisting of 24 hours in the 24-hourtimekeeping system. Ordinarily, a date is specified by a year, a month, and the sequential day within amonth (see ANSI X3.30).NOTE: A day that

32、 contains a leap second will have one extra or one less second, depending upon whetherthe leap second is positive or negative, respectively.2.7 designated civil time: A time whose representation is independent of all time differentials from UTC.Example: 9 oclock in the morning civil time in any time

33、 zone, adjusted for Daylight Saving Time, ifappropriate.2.8 civil time: The time defined in a region by the civil authorities there, adjusted for Daylight SavingTime, if appropriate.2.9 Daylight Saving Time: An instant in civil time represented with an adjustment specified by theUniform Time Act of

34、1965, as amended: “During the period commencing at 2 a.m. on the first Sunday inApril of each year and ending at 2 a.m. on the last Sunday in October, the standard time is advanced onehour except in those states that have by law exempted themselves from observance of advanced time.”NOTE: Standard ti

35、me as used in this quotation is taken to refer to civil time for the purposes of this stan-dard.2.10 coordinated universal time (UTC): “The official coordinate time scale for the Earth defined on therotating geoid.” Rec. ITU-R TF.1010, Relativistic Effects in a Coordinate Time System in the Vicinity

36、 ofthe Earth. “The time scale, maintained by the Bureau International des Poids et Mesures (BIPM), and theInternational Earth Rotation Service (IERS), which forms the basis of a coordinated dissemination ofstandard frequencies and time signals” Rec. 686, Glossary.2.11 Time-differential-from-UTC: The

37、 difference in hours and minutes between Civil time and UTC.3 Specifications3.1 Time for information interchangeTime is to be represented as civil non-daylight saving time plus a time-differential-from-UTC in the following “24-hour clock” format: HHMMSS.ssss(+, - , or *) hhmm,whereHH represents hour

38、s, MM represents minutes, SS represents seconds, ssss represents decimalfractions of a second with an unlimited number of significant digits,ANSI NCITS 310-19983and“+” or “-” represents positive or negative time differentials (respectively) from UTC,or“*” represents all time differentials from UTC w

39、orldwide,withhhmm representing hours and minutes time-differential-from-UTC.NOTE: The parenthesis symbols are not part of the representational format, but are used to indicate thatrepresentations of time will use one of the three symbols. Example: 39 minutes and 25.6 seconds past 7 oclock EST civil

40、time in the afternoon of 31 December in Philadelphia, Pennsylvania is a point in non-daylight saving time represented for interchange purposes as 193925.6-0500.Example: Designated civil time for 7 oclock in the afternoon civil time in every time zone in the world, with one-decimal-second significant

41、 digit, is represented as 190000.0*NOTE: Time-differential-from-UTC is not present in the representation of a designated civil time 3.2 Sequencing of time componentsThe sequencing of time components shall be from high order to low order (left to right): hour of the day(HH), minute of the hour (MM),

42、second of the minute (SS) with decimal seconds as appropriate: ssss,followed by the time-differential-from-UTC. Leading zeroes in each time component are required.Truncation of higher order time components (from left to right) is not permitted.3.3 Degree of specificityThe degree of specificity assoc

43、iated with time in specific information interchanges may require truncationof lower order time components (from right to left). Thus, decimal fractions of a second may be dropped,seconds and decimal fractions of a second may be dropped, or minutes and seconds and decimalfractions of a second may be

44、dropped.NOTE: The time-differential-from-UTC may not be dropped, except in representations of designated civil time as defined below.3.4 Use of separatorsNo separators are allowed in time representations for information interchange, other than those specifiedin this standard.3.5 Representation of se

45、condsThe beginning of a second within a minute of an hour of a day shall be represented by a two-digit decimalnumber ranging from 00 through 60. When a decimal fraction of a second is specified (ssss), it shall beseparated from the second representation by a decimal point (period) and expressed nume

46、rically to theprecision (number of significant digits) desired.NOTE: The allowable two-digit decimal numbers for seconds ordinarily range from 00 through 59. The two-digit decimal number 60 is reserved for representing a positive leap second. The allowed two-digit decimalnumbers range from 00 to onl

47、y 58 in the last minute of a day having a negative leap second.3.6 Representation of minutesThe beginning of a minute within an hour of the day shall be represented by a two-digit decimal numberranging from 00 through 59.ANSI NCITS 310-199843.7 Representation of hoursThe beginning of an hour of day

48、shall be represented using the 24-hour timekeeping system by recordinga two-digit decimal number ranging from 00 through 23.3.8 Representation of time-differential-from-UTCThe hours (hh) and minutes (mm) offset from UTC, expressed as a four digit number (hhmm), aremandatory for all representations o

49、f time for information interchange except that for designated civil timespecified below. A plus (+) or minus (-) precedes the four digit number (which may be zeros), indicatingthe hours and minutes the civil time is ahead of or behind UTC, respectively.3.9 Representation of UTCA specific UTC time shall be represented as HHMMSS.ssss+0000. Alternatively, the +0000 notation maybe replaced by a Z notation, as a capital letter only.3.10 Representation of designated civil timeA specified civil time independent of time zone shall be represented as HHMMSS.ssss*3.