OWN (x; 'name'; p1; p2...pn) calls an external function with data in a variate x and n scalar parameters. The function is in a DLL defined by the EXTERNAL directive, with parameters NAME='name' and NPARAMETERS=n. The directive also has a parameter RESULTS that can be set to summary to indicate that the result of the function is a scalar. Otherwise the result is a variate of the same length as x. For example:
EXTERNAL [LIBRARY='LogLik.dll'] FUNCTION='LL'; RESULT=summary;\
NPARAMETER=2
CALCULATE LogLik = OWN(X; 'LL'; a; b)