Use the File>Open>Text Import menu option to load an ascii data file in Encom PA. A minimum requirement of columns for importing ascii data is X (Easting), Y (Northing) and Z.
The Text Import (Import ASCII) utility supports the following ascii data formats:

DAT files (.dat)
Located Data files (.ldt)
Ascii files (.asc)
Text files (.txt)
Comma Delim files (.csv)
Amira TEM files (.tem)
CSV files (.csv)
Datamine files (.txt)
ERMapper ASC files (.asc)
GenSys files (.txt)
Geosoft XYZ files (.xyz)
Log ASCII Standard (LAS) files (.las)
ModelVision Line files (.lin)
ModelVision Point files (.pts)
ModelVision Hole files (.hol)
MineSight SRG files (.srg)