Refer to §20.6. There are four sources to consider, the
first three are as for any general adjustment. The
source for 
is set using the priorvar control. The source for
is set by using the betweenvar control. The source
for 
is set by using the infovar control.
In addition to these usual sources, we need also the source for the
covariances between different observations,
. This is set by using the
modelvar control, and should typically be a source different to the
one set by the infovar control. For example, suppose that ,
L, and G+U have been entered into belief store number 1, and that
G has been entered into belief store number 2. The appropriate command
line defining the belief sources is
BD>control priorvar =1,betweenvar =1,infovar =1,modelvar =2 