Octets Key Type Content
1-4 section1Length unsigned Length of section in octets (21 or nn)
5 numberOfSection unsigned Number of section (1)
6-7 centre codetable Identification of originating/generating centre (see Common Code Table C-11)
8-9 subCentre unsigned Identification of originating/generating sub-centre (allocated by originating/generating Centre)
10 tablesVersion codetable GRIB Master Tables Version Number (see Code Table 1.0 and Note 1)
11 localTablesVersion codetable Version number of GRIB Local Tables used to augment Master Tables (see Code Table 1.1 and Note 2)
12 significanceOfReferenceTime codetable Significance of Reference Time (see Code Table 1.2)
13-14 year unsigned Year (4 digits) |
15 month unsigned Month |
16 day unsigned Day | Reference time of data
17 hour unsigned Hour |
18 minute unsigned Minute |
19 second unsigned Second |
20 productionStatusOfProcessedData codetable Production status of processed data in this GRIB message (see Code Table 1.3)
21 typeOfProcessedData codetable Type of processed data in this GRIB message (see Code Table 1.4)
22 - 23 Identification template number (optional, see Code table 1.5)
24 - nn Identification template (optional, see template 1.X, where X is the identification template number given in octets 22-23)

( 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 nor missing, and local tables may include entries from the entire range of the 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.