set output filenames: src_rate, bck_rate depending on values of <withfilestem> and related params. Create a source time series expression = <srcexp> + PATTERN + FLAG selections evselect table=<table> expression=<expression> withrateset=yes rateset=src_rate Create a background time series expression = <backexp> + PATTERN + FLAG selections evselect table=<table> expression=<expression>...... withrateset=yes rateset=bck_rate