c is used to cut a data set (delete outer or inner range).
b to mark Beginning,
e to mark End,
q to Quit deleting the outer
range,
u to qUit deleting the inner range.
l or r to
select the X where X(t) is discontinuous (typically the beginning of
the reverse scan of a voltammogram) as the left or right limit,
respectively. (Starting with soas-3.2)