The offset line can be used to modify a single harmonic, rather than a range like filter or formant. It can also modify the phase. (How often this is useful is a contentious subject.)
# Example 7 starts on the next line -- file ex07 voice ex07 Wv 8 28 103 set offset 1 20 .5 split 4 condition > 0 # Example 7 ends on the previous line --
The first number after offset, 1, is the harmonic number. The second is the amplitude offset in dba. And, the third is the phase, a fraction of a cycle. So, a phase of .5 is 180 degress or pi radians.