jbdtst=0 if planet nql is not on n-body tape
jbdtst.gt.0 if planet nql is on n-body tape, in which case
we have nql=npl(jbdtst)
jbdtst.lt.0 if planet nql is on s-body tape, in which case
nql=np2(-jbdtst)

ict(39)=-2 take nothing from n-body data set (n-body tape exists
only for center of mass of solar system in compar link)
ict(39)=-1 take only moon from n-body tape if there is one
ict(39)= 0 take everything from n-body tape that is there (compar l.)
ict(39)= 1 use individual body tape whenever it is available

jct(54) = -2  take nothing from s-body data set (compar link)
jct(54) =  0  take anything from s-body data set
jct(54) =  1  take from s-body data set unless the
individual body tape is available