POLARMODE system variable
Function Description:
The POLARMODE system variable is used to set for polar tracking and object snap tracking.
Type : Bitcode 
Saved in : Registry 
Initial value : 0
The setting is stored as a bitcode using the sum of listed system variable values.
Polar angle measurements
0 : measure polar angle based on current UCS (absolute)
1 : measure polar angle from selected objects (relative)
     Object snap tracking:
0 : track orthogonally only
1 : use polar tracking settings in object snap tracking
     Use other polar tracking angles:
0 : no
4 : yes
Acquire object snap tracking points:
0 : acquire automatically
8 : press SHIFT to acquire