For a (fine-)tuning of the crystal description we recommend the use of the
command tilt. The individual faces are tilted with respect to the rest
of the crystal. The face indices can get large numbers during this
procedure. The program user should decide, whether this makes sence
(was the crystal cut?).
(Repeated) refinements of tilt, distance, and volume
should lead to an optimal crystal description.
The last refinement should always be a volume refinement, to check the quality
of the minimum of the refinement.