Insert ground surface mark
 
    File name : GRNDMRK.LSP

This program inserts '\BLOCKS\GRNDMRK.DWG' as a block. 
You can change or modify this file. Pick two point to draw ground surface.(p1,p2)
and Pick the insertion point of ground mark(p3). You dont's have to pick on the line.
Program picks the line referencing position that you picked. 
And the ground surface is inclined, then program reference the angle.