Hi Alexio, That is why I'm recommending the use of INTNX, your ensure that the "day" part of each date is set to 1 (beginning of the month). This way, when you do the PROC SORT NODUPKEY, all dates in a given month will be dedupped. With INTNX you should be able to perform that vast majority of your date transformations. The format you apply on a colum does not change the content. Thus, even if you took a date column and applied a format that does not display the day, the actual data still contains the information about the day. This is where the use if INTNX is important. Thanks,
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