Section 1 - Identification section



Octet No.	Contents
1-4	Length of section in octets (21 or nn)
5	Number of section (1)
6-7	Identification of originating/generating center (see Common Code Table C-1)
8-9	Identification of originating/generating sub-center (allocated by originating/generating center)
10	GRIB Master Tables Version Number (see Code Table 1.0 and Note 1, below) (currently 2)
11	Version number of GRIB Local Tables used to augment Master Tables (see Code Table 1.1 and Note 2, below)
12	Significance of Reference Time (see Code Table 1.2)
13-14	Year (4 digits) of reference time of data
15	Month of reference time of data
16	Day of reference time of data
17	Hour of reference time of data
18	Minute of reference time of data
19	Second of reference time of data
20	Production status of processed data in this GRIB message (see Code Table 1.3)
21	Type of processed data in this GRIB message (see Code Table 1.4)
22-nn	Reserved: need not be present


Notes:

(1) Local tables shall define those parts of the master tables which are reserved for local use except for the case described below. In any cases, the use of local tables in messages intended for non-local or international exchange is strongly discouraged.

(2) If octet 10 contains 255, then only local tables are in use. The local tables version number (octet 11) must not be zero or missing, and local tables may include entries from the entire range of tables.

(3) If octet 11 is zero, octet 10 must contain a valid master tables version number and only those parts of the tables not reserved for local use may be used.