IEEE C37.111-2013 Measuring relays and protection equipment – Part 24: Common format for transient data exchange (COMTRADE) for power systems.
This line contains time zone information for the date/time stamps in 7.4.8 and the location of the recorder. The line is composed of two fields: the time code field and the local code field. The time code is the same as the time code defined in IEEE Std C37.232 TM -2007. The field is used to specify the time difference between local time and UTC (Coordinated Universal Time scale without offset, that is, with neither local time zone or daylight saving offset). The field is restricted to a maximum of six (6) formatted characters. The first character is a sign character and is followed by up to five (5) characters for indicating the time difference (up to two (2) digits for the hours followed by the letter “h” followed by two (2) digits for the minutes). The last three (3) characters are required only when fractional hours are in use. Examples are shown below: ? “-4” means the time difference is minus 4 h (minus means time is behind UTC), ? “+1 0h30” means the time difference is plus 1 0 h and 30 min (half hour time zone), ? “-7h1 5” means the time difference is minus 7 h and 1 5 min, and ? “0” means the time difference is 0 (local time is UTC). The time difference reflects whether standard time or daylight savings time was in effect at the time of the recording. The local code is defined as the time difference between the local time zone of the recording location and UTC. If the recording device is not set to UTC, time code and local code will be the same. However, if the recording device is set to UTC, the fields will be different: local code will provide the local time zone information and the time code will be zero (“0”) irrespective of the location of the recording device. Local code will be zero (“0”) only when the local time zone is UTC. IEEE C37.111 pdf download.