mocpar = 0 compar called in midst of least squares iteration
read all three data sets iobcon, iobs, iabs1 which become in
subroutines of compar iiobcn, iiobs, iiabs1
mocpar = 1 compar called at end of least squares iteration to
calculate dummy observations
read only iobcon which become in subroutines of compar iiobcn

ndprec = 0 derivative of nutation-precession matrix not used in
determining velocities
ndprec = 1 derivative of nutation-precession matrix used in
determining velocities

nmedia =-1 effect of interplanetary media on signal is ignored
nmedia = 0 effect of interplanetary media on delay included
nmedia = 1 effect of interplanetary media on delay and delay
rate included

neatm  =-1 effect of earth atmosphere on signal is ignored
neatm  = 0 effect of earth atmosphere on delay only is
included
neatm  = 1 effect of earth atmosphere on delay and delay rate
is included

npatm  =-1 effect of planet atmosphere on signal is ignored
npatm  = 0 effect of planet atmosphere on delay only is
included
npatm  = 1 effect of planet atmosphere on delay and delay rate
is included

nintrf =-1 interferometry observables are delay and/or delay
rate (conventional vlbi)
nintrf = 0 interferometry observable is accumulated cycle
count
nintrf = 1 interferometry observable is phase

*  start=600
read observation library tape and process iobcon
data set to alter error weightings or setup
dummy observations

(2) counted-cycle vlbi (or one-way doppler) observations
(nintrf=0, ncode=1)
observable is accumulated cycle count over the interval from utrec
- tc at the initial observation to the current utrec. if the cal-
culation of transmit frequency for each observation requires
use of the delay difference over a count interval to get
beta (=v/c), then ferctl is called twice, once at the start
and once at the end of the current count interval.  with idopob
= 0, fermtr calls ferctl to setup for beginning of count interval.
ferctl calls fermn or fersb for calculations, sets idopob = 1, and
returns to fermtr.  fermtr then calls ferctl a second time
for calculations at the end of the count interval; ferctl calls
fermn or fersb and this time returns idobob= -1.  the first
pass through ferctl is eliminated if the begin time of the current
observation interval is the same as the final time of the previous
interval.  in this case, ferctl merely updates the old information
and returns from the first call  with idopob =-1.  even if beta
is calculated using instantaneous velocities, this logic is still
used for the first observation in the series.
in either case, partl is called twice for
the first observation (nk1=-1,0) but only once thereafter (nk1=1),
the partials being calculated using the current delay minus the
initial delay with the transmit frequency assumed constant.

(3) observations are phase (nintrf=1, ncode=1)
observable is absolute but ambiguous (modulo 1 cycle) phase at
utrec.  since the received frequency may need to be calculated
from differenced phases, this observable is calculated in the
same way as the counted-cycle observable except that the
quantity subtracted at the initial epoch is zero.

idopob= 0 when ferctl first called for observation
idopob= -1 set in ferctl on second call (interf called
second time only if idopob was set = 1 on
first call