| Bit No. | Value | Meaning |
|---|---|---|
| 1 |
0 |
Points in the first row or
column scan in the +i (+x) direction |
| 1 |
Points in the first row or column scan in the -i (-x) direction | |
| 2 |
0 |
Points in the first row or column scan in the -j (-y) direction |
| 1 |
Points in the first row or column scan in the +j (+y) direction | |
| 3 |
0 |
Adjacent points in the i (x)
direction are consecutive |
| 1 |
Adjacent points in the j (y) direction are consecutive | |
| 4 | 0 | All rows scan in the same direction |
| 1 | Adjacent rows scan in the opposite direction | |
| 5 | 0 | Points within odd rows are not offset in i(x) direction |
| 1 | Points within odd rows are offset by Di/2 in i(x) direction | |
| 6 | 0 | Points within even rows are not offset in i(x) direction |
| 1 | Points within even rows are offset by Di/2 in i(x) direction | |
| 7 | 0 | Points are not offset in j(y) direction |
| 1 | Points are offset by Dj/2 in j(y) direction | |
| 8 | 0 | Rows have Ni grid points and columns have Nj grid points |
| 1 | Rows have Ni grid points if points are not offset in i direction Rows have Ni-1 grid points if points are offset by Di/2 in i direction Columns have Nj grid points if points are not offset in j direction Columns have Nj-1 grid points if points are offset by Dj/2 in j direction |
| Notes: 1. i direction - West to east along a parallel or left to right along an x-axis. 2. j direction - South to north along a meridian, or bottom to top along a y-axis. 3. If bit number 4 is set, the first row scan is defined by previous flags. 4. La1 and Lo1 define the first row, which is an odd row. 5. Di and Dj are assumed to be positive, with the direction of i and j being given by bits 1 and 2. 6. Bits 5 through 8 may be used to generate staggeblack grids, such as Arakawa grids (see Attachment, Volume 1.2, Part A, Att. GRIB). 7. If any of bits 5, 6, 7 or 8 are set, Di and Dj are not optional. |