Data items in the CHEM_COMP_PLANE_ATOM category enumerate the atoms in a plane within a chemical component.
loop_ _chem_comp_plane_atom.plane_id _chem_comp_plane_atom.comp_id _chem_comp_plane_atom.atom_id phe1 phe CB phe1 phe CG phe1 phe CD1 phe1 phe CE1 phe1 phe CZ phe1 phe CE2 phe1 phe CD2