The header has 6 lines:
north: xxxxxx.xx
south: xxxxxx.xx
east: xxxxxx.xx
west: xxxxxx.xx
rows: r
cols: c
The north, south, east, and west field values entered
are the coordinates of the edges of the geographic region.
The rows and cols field values entered describe the dimensions
of the matrix of data to follow.
The data which follows is r rows of c integers.
Optionally the following parameters can be defined in the header section:
null: nn
type: float
multiplier: 2.
"null" defines a string or number to be converted to NULL value (no
data).
"type" defines the data type (int, float double) as is not required.
"multiplier" is an optional parameter to multiply each cell value.
The data (which follows the header section) must contain r x c values, but it is not necessary that all the data for a row be on one line. A row may be split over many lines.
r.in.ascii handles floating point cell values.
The header information in ESRI Raster ASCII files differs from GRASS. To convert an Arc/Info (ArcView) ASCII grid file into GRASS, click here. Also, see r.in.arc to import ESRI Raster ASCII files.