rfc3339.txt

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   datespec-full     = datepart-fullyear date-month ["-"] date-mday
   datespec-year     = date-century / dateopt-century date-year
   datespec-month    = "-" dateopt-year date-month [["-"] date-mday]
   datespec-mday     = "--" dateopt-month date-mday
   datespec-week     = datepart-wkyear "W"
                       (date-week / dateopt-week date-wday)
   datespec-wday     = "---" date-wday
   datespec-yday     = dateopt-fullyear date-yday

   date              = datespec-full / datespec-year
                       / datespec-month /
   datespec-mday / datespec-week / datespec-wday / datespec-yday

Time:

   time-hour         = 2DIGIT ; 00-24
   time-minute       = 2DIGIT ; 00-59
   time-second       = 2DIGIT ; 00-58, 00-59, 00-60 based on
                              ; leap-second rules
   time-fraction     = ("," / ".") 1*DIGIT
   time-numoffset    = ("+" / "-") time-hour [[":"] time-minute]
   time-zone         = "Z" / time-numoffset

   timeopt-hour      = "-" / (time-hour [":"])
   timeopt-minute    = "-" / (time-minute [":"])

   timespec-hour     = time-hour [[":"] time-minute [[":"] time-second]]
   timespec-minute   = timeopt-hour time-minute [[":"] time-second]
   timespec-second   = "-" timeopt-minute time-second
   timespec-base     = timespec-hour / timespec-minute / timespec-second

   time              = timespec-base [time-fraction] [time-zone]

   iso-date-time     = date "T" time

Durations:

   dur-second        = 1*DIGIT "S"
   dur-minute        = 1*DIGIT "M" [dur-second]
   dur-hour          = 1*DIGIT "H" [dur-minute]
   dur-time          = "T" (dur-hour / dur-minute / dur-second)
   dur-day           = 1*DIGIT "D"
   dur-week          = 1*DIGIT "W"
   dur-month         = 1*DIGIT "M" [dur-day]
   dur-year          = 1*DIGIT "Y" [dur-month]
   dur-date          = (dur-day / dur-month / dur-year) [dur-time]

   duration          = "P" (dur-date / dur-time / dur-week)



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RFC 3339       Date and Time on the Internet: Timestamps       July 2002


Periods:

   period-explicit   = iso-date-time "/" iso-date-time
   period-start      = iso-date-time "/" duration
   period-end        = duration "/" iso-date-time

   period            = period-explicit / period-start / period-end

Appendix B. Day of the Week

   The following is a sample C subroutine loosely based on Zeller's
   Congruence [Zeller] which may be used to obtain the day of the week
   for dates on or after 0000-03-01:

   char *day_of_week(int day, int month, int year)
   {
      int cent;
      char *dayofweek[] = {
         "Sunday", "Monday", "Tuesday", "Wednesday",
         "Thursday", "Friday", "Saturday"
      };

      /* adjust months so February is the last one */
      month -= 2;
      if (month < 1) {
         month += 12;
         --year;
      }
      /* split by century */
      cent = year / 100;
      year %= 100;
      return (dayofweek[((26 * month - 2) / 10 + day + year
                        + year / 4 + cent / 4 + 5 * cent) % 7]);
   }

Appendix C. Leap Years

   Here is a sample C subroutine to calculate if a year is a leap year:

   /* This returns non-zero if year is a leap year.  Must use 4 digit
      year.
    */
   int leap_year(int year)
   {
       return (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
   }





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RFC 3339       Date and Time on the Internet: Timestamps       July 2002


Appendix D. Leap Seconds

   Information about leap seconds can be found at:
   <http://tycho.usno.navy.mil/leapsec.html>.  In particular, it notes
   that:

      The decision to introduce a leap second in UTC is the
      responsibility of the International Earth Rotation Service (IERS).
      According to the CCIR Recommendation, first preference is given to
      the opportunities at the end of December and June, and second
      preference to those at the end of March and September.

   When required, insertion of a leap second occurs as an extra second
   at the end of a day in UTC, represented by a timestamp of the form
   YYYY-MM-DDT23:59:60Z.  A leap second occurs simultaneously in all
   time zones, so that time zone relationships are not affected.  See
   section 5.8 for some examples of leap second times.

   The following table is an excerpt from the table maintained by the
   United States Naval Observatory.  The source data is located at:

      <ftp://maia.usno.navy.mil/ser7/tai-utc.dat>





























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RFC 3339       Date and Time on the Internet: Timestamps       July 2002


   This table shows the date of the leap second, and the difference
   between the time standard TAI (which isn't adjusted by leap seconds)
   and UTC after that leap second.

   UTC Date  TAI - UTC After Leap Second
   --------  ---------------------------
   1972-06-30     11
   1972-12-31     12
   1973-12-31     13
   1974-12-31     14
   1975-12-31     15
   1976-12-31     16
   1977-12-31     17
   1978-12-31     18
   1979-12-31     19
   1981-06-30     20
   1982-06-30     21
   1983-06-30     22
   1985-06-30     23
   1987-12-31     24
   1989-12-31     25
   1990-12-31     26
   1992-06-30     27
   1993-06-30     28
   1994-06-30     29
   1995-12-31     30
   1997-06-30     31
   1998-12-31     32























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RFC 3339       Date and Time on the Internet: Timestamps       July 2002


Acknowledgements

   The following people provided helpful advice for an earlier
   incarnation of this document:  Ned Freed, Neal McBurnett, David
   Keegel, Markus Kuhn, Paul Eggert and Robert Elz.  Thanks are also due
   to participants of the IETF Calendaring/Scheduling working group
   mailing list, and participants of the time zone mailing list.

   The following reviewers contributed helpful suggestions for the
   present revision: Tom Harsch, Markus Kuhn, Pete Resnick, Dan Kohn.
   Paul Eggert provided many careful observations regarding the
   subtleties of leap seconds and time zone offsets.  The following
   people noted corrections and improvements to earlier drafts: Dr John
   Stockton, Jutta Degener, Joe Abley, and Dan Wing.

Authors' Addresses

   Chris Newman
   Sun Microsystems
   1050 Lakes Drive, Suite 250
   West Covina, CA 91790 USA

   EMail: [e-mail]


   Graham Klyne (editor, this revision)
   Clearswift Corporation
   1310 Waterside
   Arlington Business Park
   Theale, Reading  RG7 4SA
   UK

   Phone: [phone]
   Fax:   [phone]
   EMail: [e-mail]
















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RFC 3339       Date and Time on the Internet: Timestamps       July 2002


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Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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