09-13-2016 05:18 PM
I would recommend making three datasets with just a few observations each and see for yourself. Try putting a PUT statement before the OUTPUT statement. That is especially useful for looking at the values of M, N and _N_ which will not be in the WANT dataset.
09-14-2016 01:52 AM
This seems to do a complete cartesian join over all three datasets, in a very complicated and inefficient manner. Would need some test data to verify that.