b,side - lhs, rhs of normal equations
sav    - work area (nsize r*8)
iptr   - mapping ptr array from saved to current parameter set
nsize  - neq rank
imats  - input data set
mesmt1,ermes1 - returned num and sumsq added (unless jmata.ne.0)
weight - overall weighting factor for incrementing b,side
ntape1,nseq1 - used in series-by-series save
jmata  - flag for skipping lhs or rhs+stats
itdif,prmdif - used in DPSNEC
znsq   - correction to sumsq from prereduction
sumzns - accumulated correction to sumsq
measmt,ermeas - cumulative total num and sumsq
iuseap - flag for restoring imbedded a prioris, instead of ordinary
information. if >0, don't update statistics or print summary
iaprio - flag for existence of imbedded a priori information
this flag is 0 for Ibuf2, which is purely a priori, so that
nrmadd won't try to skip over (non-existent) ordinary stuff
ivectk - if >0 then restore k vector 'vectk'
wgtk  - weight for k vector restoration
sumzsm - total correction to sum (o-c/error) due to prereduction
zsm - incremental addition to sumzsm from latest data set
sumsqa - contribution of a priori constraints to sumsq (o-c/error)
sumaps - accumulated a priori sumsq