acknowledgements for ansi/nist-itl 1-2011 - NIST Visual Image ...

ANSI/NIST-ITL 1-2011 - UPDATE 2013 DRAFT VERSION7.7.2 Date and timeDate and time are used in several fields and information items throughout the standard.They are handled differently for each encoding (See Annex B and Annex C).7.7.2.1 GeneralYYYY designates the four-digit year; MM designates the month (01 through 12); DDrepresents the day of the month (01 through 31); hh represents the hour (00 through 23); mmrepresents the minute (0 through 59); and ss represents the seconds (0 through 59).Midnight is expressed as all zeros in the time portion of the date and time.The time and date fields are handled differently for each encoding. The Traditional encodingrepresents the time and date as a numeric value (such as “20110308” representing March 8,2011). NIEM-conformant encoding places the date in an element formatted as “2011-03-08”. The value is shown as “2011-03-08T05:25:00Z” in the case of Greenwich mean time(See Section 7.7.2.2). The “T” is a fixed character that indicates the separation of the dateand the time in the alphanumeric string. In all cases, the content shall be identical, regardlessof the encoding. See Annex B: Traditional encoding and Annex C: NIEM-conformantencoding rules for details.7.7.2.2 Greenwich mean time (coordinated universal time – UTC) / GMTUTC has replaced GMT as the main reference time scale terminology, but the olderterminology is retained in this standard for existing record types. In this standard, Field1.014 Greenwich mean time / GMT shall be taken to mean the UTC value. Some newerrecord types using this format refer to the data as UTC (such as in Field 18.013: Samplecollection date / SCD). This time is independent of the actual time zone where the timeand date is recorded. The data is YYYYMMDDhhmmssZ, where the Z is indicates the zonedescription of 0 hours. This data is handled differently for each encoding.7.7.2.3 Local dateThe local date is recorded as YYYYMMDD. It may be a different date than the GMT, dueto time zone differences. It is handled differently for each encoding.7.7.2.4 Local date & timeThe local date and time is recorded as YYYYMMDDhhmm. Note that this may be adifferent date than the corresponding GMT, due to time zone differences. It is reflective ofthe local time, such as Daylight Savings Time. This data is handled differently for eachencoding.7.7.2.5 Time index / TIXFor Type-20 or Type-21 records containing video or audio, this field shall contain twoinformation items, time index start /TIS and time index end / TIE for the start and endtimes of segments within a video or audio file, measured in hh:mm:ss. sss where ss. sss refersto the seconds and milliseconds. Thus, the allowed special characters are the colon andthe period. TIX is comprised of one or more subfields. Each subfield corresponds to aMay, 2013 DRAFT VERSION UPDATE 2013 Page 57