The ODS OUTPUT statement opens the Output destination. By default, the list for the Output destination is EXCLUDE ALL. This ODS OUTPUT statement puts ParameterEstimates in the selection list for the destination.

The MATCH_ALL option produces a SAS data set for each instance of ParameterEstimates. PERSIST=PROC ensures that the data set definition endures even when the procedure step ends. The name of the first data set is IronParameterEstimates. The name of the second data set is IronParameterEstimates1, and so on. 

ods output ParameterEstimates(match_all persist=proc)
           =IronParameterEstimates;