IP
Command
line: ip
Description:
insert new
points with elevation calculated by interpolation
TopoLT
toolbar: 
Menu:
By using this command you can introduce new points that have
elevation calculated by interpolation. New points can be introduced on
interpolation line or outside it. If new points will be outside line then
elevation will be calculated reported to perpendicular position at
interpolation line.
The new point’s code you introduce will consist from the
first selected point’s code and the code allocated for graphical points
(accordingly to configuration section Points).