group {<xray-average-group-statement>} end
<xray-average-group-statement> :==
[mask=<real-space-object>]
The real space object containing an averaging mask. This mask covers
the primary molecule (group 1). If this mask is not defined for a group
then it will be generated from the mask of the primary group (group 1).
This decreases the amount of memory required at the cost of increased
computing time.
<matrix>
The rotation matrix for this group.