Section 2: Grid description section
| Octets | Key | Type | Content |
| 1-3 | section2Length | unsigned | Length of section (octets) |
| 4 | numberOfVerticalCoordinateValues | unsigned | NV number of vertical coordinate parameters |
| 5 | pvlLocation | unsigned | PV location (octet number) of the list of vertical coordinate parameters, if present; or PL location (octet number) of the list of numbers of points in each row (if no vertical coordinate parameters are present), if present; or 255 (all bits set to 1) if neither are present |
| 6 | dataRepresentationType | codetable | Data representation type (see Code table 6) |
| 7-32 | Grid definition (according to data representation type octet 6 above) | ||
| 33-42 | Extensions of grid definition for rotation or stretching of the coordinate system or Lambert conformal projection or Mercator projection | ||
| 33-44 | Extensions of grid definition for space view perspective projection | ||
| 33-52 | Extensions of grid definition for stretched and rotated coordinate system | ||
| PV | List of vertical coordinate parameters (length = NV × 4 octets); if present, then PL = 4NV + PV | ||
| PL | List of numbers of points in each row (length = NROWS x 2 octets, where NROWS is the total number of rows defined within the grid description) |
( 1) Vertical coordinate parameters are used in association with hybrid vertical coordinate systems.
( 2) Hybrid systems, in the context, employ a means of representing vertical coordinates in terms of a mathematical combination of pressure and sigma coordinates. When used in conjunction with a surface pressure field and an appropriate mathematical expression, the vertical coordinate parameters may be used to interpret the hybrid vertical coordinate.
( 3) Each vertical coordinate parameter is represented in 4 octets, using the scheme for representing floating point numbers described in Regulation 92.6.4.