The class ABA_SUB represents a subproblem of the implicit enumeration, i.e., a node of the branch-and-bound tree. The subproblem optimization is performed by the solution of linear programming relaxations. Usually, most running time is spent within the member functions of this class. Also from the class ABA_SUB a new class has to be derived for each new application. By redefining virtual functions in the derived class problem specific algorithms as, e.g., cutting plane or column generation, can be embedded.