The following code shows the format for a Grid layout that has 50 by 30 data points:
! Grid has 50 by 30 points
! Holes have a value of 100.0
! Grid increases in X steps of 1.0 and Y steps of 2.0
!Origin of grid is at X = -20, Y = 50
GRID 50 30 100.0 1.0 2.0 -20.0 50.0
! 1500 data values follow, one for each grid point
49.875000 43.765625 38.500000 33.984375 30.12400
26.828125 24.000000 21.235610 48.877940 17.39770
. . .Line 5 indicates that the file format is Grid, and the file contains 50 by 30 data points. Line 6 indicates the hole value (100.0), the X and Y increments (1.0 and 2.0), and the coordinates for the origin.