In general,Oddleg
calipers
are used to scribe a line a set distance from the edge of
workpiece. The bent leg is used to run along the workpiece edge
while the scriber makes its mark at a predetermined distance, this
ensures a line parallel to the edge.There is a caliper which has a
slight shoulder in the bent leg allowing it to sit on the edge
more securely, thelcaliper which lacks this feature but has a
renewable scriber that can be adjusted for wear, as well as being
replaced when excessively worn.