The 0-goal is also known as a null goal or empty goal.

In the C++ API, a null goal is an IloCplex::Goal handle object with a null (0) implementation pointer.

A null goal can also be returned by the method IloCplex::GoalI::execute.

Use a null goal when you want to instruct ILOG CPLEX not to branch any further. For example, when CPLEX finds a feasible solution, and you want to accept it without further branching, a null goal is appropriate.

For example, the following sample from the C++ API accepts an integer feasible solution and stops branching.

if ( isIntegerFeasible() )
   return 0;