The USEQPR parameter controls the Quadratic Recognition option. This option consists of an algebraic preprocessor that automatically determines if an arbitrary nonlinear model is actually a quadratic programming (QP) model. If a model is found to be a convex QP, then it can be passed to the faster quadratic solver. Note that the QP solver is not included with the base version of LINGO, but comes as part of the Barrier option.

LINGO defaults to  using quadratic recognition.