Import GRASS data to ARC V.6

[Don L. Sawatzky]

I am using "imageread" command in ARC6 to import GRASS v.4 cell layers into
ARC coverages.  Some cell layers will import; others will not.  Seems that
only cell layers created under GRASS v.3 will import; new layers created
with GRASS v.4 apparently not.  ARC complains that it can't open some cell
layers; yet does open an process others.  Are there differences in cell
layers in v.3 and v.4?