@ErikLund_Jensen  "and I have more than once seen SAS employees use it in production code" That clearly demonstrates that SAS employees are also only people and far from perfect. Who would have thought 🙂   I agree with you that monotonic() appears to be very reliable if used with SAS tables. But it's still not documented and supported and if something should ever fall over because of monotonic() then you're on your own. I guess SAS TechSupport would still help you as that's what they just do - but I assume they would only go so far until you're told that you have to change your logic to something which doesn't use monotonic(). On top of it: Because monotonic() has never been production you also risk that it's suddenly no more implemented in a future SAS release which could cause quite a few migration headaches if used regularly. ... View more