SHOWNL Command
The SHOWNL command will cause LINGO to generate the model and then display only those rows that contain nonlinearities. Please refer to the Types of Constraints section for a discussion of linear vs. nonlinear expressions.
In general, one would prefer to always have purely linear models. Linear models solve faster and will always converge to a global solution. Therefore, when developing a model, you will be interested in carefully evaluating nonlinearities to see if they can either be eliminated or rewritten in a linear fashion. The SHOWNL command is helpful in tracking down a model's nonlinearities.