ACOLS=(C1,C2,C3,C4) Columns in the first IBIS tabular file that
contain the tiepoints. C1 has new line,
C2 has new sample, C3 has old line, and
C4 has old sample. The defaults are
(1,2,3,4).
BCOLS=(C5,C6,C7,C8) Columns in the second IBIS tabular file that
contain the tiepoints. C5 has new line,
C6 has new sample, C7 has old line, and
C8 has old sample. The defaults are
(1,2,3,4).