GEOPAK-NAVIGATOR-EDIT ELEMENT TANGENT

Hello,

I am learning Geopak V8i SS2 using the Create Horizontal Alignments Learning Path and the help file as it applies.

I have selected Tools->Navigator->set Element to Curves->Id element->Tools->Edit Element->Store Curve by Tangents->change the Back Tangent value to the third option from top and used a 30ft Tangent Distance.  However, I want to put the curve back the way it was originally and it will not move back if I reset the tangent distance to 0.  Why will the curve not move back?