patt_cross [heavy atom molecule name] [xmin xmax ymin ymax zmin zmax]
This creates an object of all of the desired heavy atoms within the selected volume. The volume must be defined in fractional unit cell units. The cross vectors are put as atoms in molecule PATT (which must exist) and an object created. The command remains active. If a heavy atom position is being changed with Patt_move the cross vector coordinates and object are updated. If a cross vector is identified, the residue type field gives the from/to heavy atom.