In the Callable Library, query or diagnostic callbacks are organized into two groups: LP callbacks (that is, continuous callbacks) and MIP callbacks (that is, discrete callbacks). For each group, one callback function can be set by the routine CPXsetlpcallbackfunc and one by CPXsetmipcallbackfunc. You can distinguish between the actual callbacks by querying the argument wherefrom passed to the callback function as an argument by ILOG CPLEX.

The continous callback is also called during the solution of problems of type LP, QP, and QCP.