system numeric
The level of validation checking done on new polygon entities. The various levels are:
0 - Checks for coplanarity. All vertices should be in the same 3-D plane. Adjustments are made where necessary.
1 - Checks for coplanarity. Checks for coincident vertices. Checks for slivers.
2 - Checks for coplanarity. Checks for coincident vertices, Checks for slivers. Checks for crossovers.
The default value at system startup is 1.
The same check using polygon_validation is also performed on a polygon whenever its vertex list changes.