cellhd format: 3 ??

[Bruce Wylie]

I am trying to take grass files to LAS. The files brought from LAS to grass
(which worked) had the following cellhd:

proj:       0
zone:       0
north:      100
south:      1
east:       600
west:       1
cols:       600
rows:       100
e-w resol:  0.99833333
n-s resol:  0.99
format:     0
compressed: 0


The cellhd file for the grass file which did not go into LAS was:

proj:       0
zone:       0
north:      100
south:      1
east:       600
west:       1
cols:       600
rows:       100
e-w resol:  0.99833333
n-s resol:  0.99
format:     3
compressed: 0

What does the "format:  3" mean and how can I convert it to "format:  0"?

Thanks,
B. Wylie