XmlmmCIF equivalent: chemical_conn_atom Data items in the CHEMICAL_CONN_ATOM category would not, in general, be used in a macromolecular CIF. See instead the ENTITY data items. Data items in the CHEMICAL_CONN_ATOM and CHEMICAL_CONN_BOND categories record details about the 2D chemical structure of the molecular species. They allow a 2D chemical diagram to be reconstructed for use in a publication or in a database search for structural and substructural relationships. The CHEMICAL_CONN_ATOM data items provide information about the chemical properties of the atoms in the structure. In cases where crystallographic and molecular symmetry elements coincide they must also contain symmetry-generated atoms, so that the CHEMICAL_CONN_ATOM and CHEMICAL_CONN_BOND data items will always describe a complete chemical entity. XmlmmCIF equivalent: chemical_conn_atom/NCA The number of connected atoms excluding terminal hydrogen atoms. XmlmmCIF equivalent: chemical_conn_atom/NH The total number of hydrogen atoms attached to this atom, regardless of whether they are included in the refinement or the ATOM_SITE list. This number is the same as _atom_site.attached_hydrogens only if none of the hydrogen atoms appear in the ATOM_SITE list. XmlmmCIF equivalent: chemical_conn_atom/charge The net integer charge assigned to this atom. This is the formal charge assignment normally found in chemical diagrams. XmlmmCIF equivalent: chemical_conn_atom/display_x The 2D Cartesian x coordinate of the position of this atom in a recognisable chemical diagram. The coordinate origin is at the lower left corner, the x axis is horizontal and the y axis is vertical. The coordinates must lie in the range 0.0 to 1.0. These coordinates can be obtained from projections of a suitable uncluttered view of the molecular structure. If absent, values will be assigned by the journal or database staff. XmlmmCIF equivalent: chemical_conn_atom/display_y The 2D Cartesian y coordinate of the position of this atom in a recognisable chemical diagram. The coordinate origin is at the lower left corner, the x axis is horizontal and the y axis is vertical. The coordinates must lie in the range 0.0 to 1.0. These coordinates can be obtained from projections of a suitable uncluttered view of the molecular structure. If absent, values will be assigned by the journal or database staff. XmlmmCIF equivalent: chemical_conn_atom/type_symbol This data item is a pointer to _atom_type.symbol in the ATOM_TYPE category. XmlmmCIF equivalent: chemical_conn_atom/number The chemical sequence number to be associated with this atom. Within an ATOM_SITE list this number must match with one of the _atom_site.chemical_conn_number values.