I recently found PROC SQL's monotonic function in the Tips and Techniques section of the Amadeus web site. It's not documented or supported, so it should be used with caution.
proc sql;SAS Usage Note 15138 says that the monotonic function is not supported in PROC SQL and that using the monotonic function in PROC SQL can cause missing or non-sequential values to be returned.
create table notecolon as
select * , monotonic() as counter
In the right circumstances, the monotonic function can be useful. And Amadeus have plenty more useful tips and techniques to peruse and use!