I am trying to write a lisp for construction staking in ldd. Basically what I am doing is having a person pick two endpoints of a line that is xrefed in. With these two points I will use them to draw a terrain 3d polyline then place points along the line and calculate the elevations automatically. However I am very new to lisp and they way i was doing it was storing the input when the select the two lines then entering them in for all the commands. I do not know some of the command aliases for LDD. How do you run a command and set the variables for that command if you do not know the alias?