The errors (neterr) in each channel as listed in the _obs.tab file are given by:
neterr=sqrt (src_less_part_err**2 + bkgd_norm_err**2)
where src_less_part_err is the error on: the source counts less
the source charged particle counts; and bkgd_norm_err is the error
on: the background counts less the background charged particle count,
normalized by the ratio of source area to background area, by the
vignetting ratio of effective areas, and by any user-supplied factor.
The error on each count is estimated from the count on the assumption that it arises from a Poisson process (by default). The error on each sum or difference of counts is estimated as the sum in quadrature of the estimated errors on the constituent counts.
If a systematic error is applied (this is the default for the IPC: pkgpars.ein_ipc_syserr=``0.03'' and qpspec.syserr=``'') then
final_neterr=sqrt(neterr**2+[net*syserr]**2)
Parameter names are, as far as possible, identical to those in the _obs.tab file.