mKeyName
String = "" The name of the value.
A bool driver that reads a named value stored on a map
prop as a bool. It reads the same table as
GetMapPropFloatDynamicMaterialFloatDriver
and is true when the value under mKeyName is not 0.
The source must be a map prop. The driver returns false without one, and when the prop
has no value under that name.
String = "" The name of the value.