The @APISET() statement is used in calc sections to set options in the LINDO API (LINGO’s solver engine) that aren’t available through the standard option set in LINGO.  The argument list consists of a parameter-id (an integer value), a string specifying if the parameter is an integer or a double precision value, and the parameter value.  More information on the parameters available in the LINDO API may be found in the LINDO API documentation and the Lindo.h header file included with your LINGO installation.