You can't use monotonic() interchangeable with first. processing of the data step. It' more like the _n_ variable. But if it fits your current need, great. To be able to use first. processing in DIS, you need to use User Written code, there is no "pure" data step transformation available. About montonic() being unsupported, one funny thing is that is now being used within the Data Validation transformation. Wonder if SAS is supporting that... ... View more