Suppose you want to display the CA-trace of a protein from residues B1 to B100, plus a sphere of atoms around residue B50. If the molecule is called M15, the following commands will create the desired object:
mol m15 obj mol1 ca b1 b100 centre_atom b50 ; sphere 10.0 end
If you quit the program, and come back later, the object will still exist. The object can be deleted with the command:
del_obj mol1 ;