read /tmp/pw-unc.sac /tmp/pw-unc.sac /tmp/pw-unc.sac mul 1 0 -1 ;* pos., zero and neg. uncertainty addf /tmp/pw-sum.sac /tmp/pw-sum.sac /tmp/pw-sum.sac ch file 1 kevnm +1_sigma ;* name traces for P2 ch file 2 kevnm stack_sum ch file 3 kevnm -1_sigma fileid type list kevnm ;* KEVNM identifies trace line list 5 1 5 increment on ;* unc traces dashed p2 ;* overlay three plot traces