The SOS type
[DataContract] public enum SOSType : byte
A SOS1 is a set of variables in which
A SOS2 is a set of variables in which
The set of variables appearing in an equation with only binary variables and +1 or -1 coefficients, and a right-hand-side value of 1 - (number of '-1 coefficients'). This is a special case of SOS1.