See v1.0 Record Format Tables for the record structure outside of payload.
| Offset | Length | Type | Description |
| byte | byte | ||
| 16 | 4 | character | member name |
| 20 | 8 | integer [2] | valid times |
| 28 | 12 | character [2][6] | plane names |
| 40 | 6 | character | element name |
| 46 | 2 | --- | reserved |
| 48 | 2 * 4 | integer[2] | nx and ny: number of grid points in X and Y directions |
| 56 | 4 | character | packing scheme such as "2PAC" |
| 60 | 4 | character | "NONE" |
| 64 | ... | ... | PACKED DATA: see following description |
| Offset | Length | Type | Description |
| byte | byte | ||
| 16 | 4 | character | member name |
| 20 | 8 | integer [2] | valid times |
| 28 | 12 | character [2][6] | plane names |
| 40 | 6 | character | element name |
| 46 | 2 | --- | reserved |
| 48 | 2 * 4 | integer[2] | nx and ny: number of grid points in X and Y directions |
| 56 | 4 | character | packing scheme such as "2PAC" |
| 60 | 4 | character | "UDFV" |
| 64 | (various) | integer/floating | missing value |
| ... | ... | ... | PACKED DATA: see following description |
| Offset | Length | Type | Description |
| byte | byte | ||
| 16 | 4 | character | member name |
| 20 | 8 | integer [2] | valid times |
| 28 | 12 | character [2][6] | plane names |
| 40 | 6 | character | element name |
| 46 | 2 | --- | reserved |
| 48 | 2 * 4 | integer[2] | nx and ny: number of grid points in X and Y directions |
| 56 | 4 | character | packing scheme such as "2PAC" |
| 60 | 4 | character | "MASK" |
| 64 | 4 | integer | n_ms: number of bytes used for mask bitmap |
| 68 | n_ms | bitmap | mask bitmap |
| ... | ... | ... | PACKED DATA: see following description |
When the packing scheme is 1PAC, 2PAC, or 2UPC,
two 4-byte floating-point field base and amp
is followed by an array of packed type.
See Reference Manual about the packed type.
Unpacking is adding base after multiplying amp.
When the packing scheme is 4PAC, it is similar to 2PAC but
base and amp is 8-byte floating-point value.
When the packing scheme is RLEN,
three 4-byte integer field nbit, maxv, num
is followed by octet stream containing compressed bit stream.
When the packing scheme is GRIB,
the GRIB octet stream itself will be the packed data;
although this feature is not implemented yet.
Otherwise, the packed data is array of packed type.
Note that if the packing scheme is 'N1I2' the packed value
is 10 times of unpacked value.