* this is the ALASKA94 geoid grid
A ALASKA94(NGS)   ala94

* this is the GEOID93 (East) geoid grid
E GEOID93 (NGS)   geoid93e

* this is the GEOID93 (Central) geoid grid
C GEOID93 (NGS)   geoid93c

* this is the GEOID93 (West) geoid grid
W GEOID93 (NGS)   geoid93w

* this is the GEOID93 (Hawaii) geoid grid
H GEOID93 (NGS)   haw93

* this is the GEOID93 (PR/VI) geoid grid
P GEOID93 (NGS)   prvi93