In section C, the definitions of groups of chemical elements are as follows: Alkali metals: Li, Na, K, Rb, Cs, Fr Alkaline earth metals: Ca, Sr, Ba, Ra Lanthanides: elements with atomic numbers 57 to 71 inclusive Rare earths: Sc, Y, Lanthanides Actinides: elements with atomic numbers 89 to 103 inclusive Refractory metals: Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W Halogens: F, Cl, Br, I, At Noble gases: He, Ne, Ar, Kr, Xe, Rn Platinum group: Os, Ir, Pt, Ru, Rh, Pd Noble metals: Ag, Au, Platinum group Light metals: alkali metals, alkaline earth metals, Be, Al, Mg Heavy metals: metals other than light metals Iron group: Fe, Co, Ni Non-metals: H, B, C, Si, N, P, O, S, Se, Te, noble gases, halogens Metals: elements other than non-metals Transition elements: elements with atomic numbers 21 to 30 inclusive, 39 to 48 inclusive, 57 to 80 inclusive, 89 upwards Section C covers: pure chemistry, which covers inorganic compounds, organic compounds, macromolecular compounds, and their methods of preparation; applied chemistry, which covers compositions containing the above compounds, such as: glass, ceramics, fertilisers, plastics compositions, paints, products of the petroleum industry. It also covers certain compositions on account of their having particular properties rendering them suitable for certain purposes, as in the case of explosives, dyestuffs, adhesives, lubricants, and detergents; certain marginal industries, such as the manufacture of coke and of solid or gaseous fuels, the production and refining of oils, fats and waxes, the fermentation industry (e.g., brewing and wine-making), the sugar industry; certain operations or treatments, which are either purely mechanical, e.g., the mechanical treatment of leather and skins, or partly mechanical, e.g., the treatment of water or the prevention of corrosion in general; metallurgy, ferrous or non-ferrous alloys. In the case of operations, treatments, products or articles having both a chemical and a non-chemical part or aspect, the general rule is that the chemical part or aspect is covered by section C. In some of these cases, the chemical part or aspect brings with it a non-chemical one, even though purely mechanical, because this latter aspect either is essential to the operation or treatment or constitutes an important element thereof. It has seemed, in fact, more logical not to dissociate the different parts or aspects of a coherent whole. This is the case for applied chemistry and for the industries, operations and treatments mentioned in Notes (1)(c), (d) and (e). For example, furnaces peculiar to the manufacture of glass are covered by class and not by class . There are, however, some exceptions in which the mechanical (or non-chemical) aspect carries with it the chemical aspect, for example: Certain extractive processes, in subclass ; The chemical purification of air, in subclass ; Chemical methods of fire-fighting, in subclass ; Chemical processes and apparatus, in class ; Impregnation of wood, in subclass ; Chemical methods of analysis or testing, in subclass ; Photographic materials and processes, in class , and, generally, the chemical treatment of textiles and the production of cellulose or paper, in section D. In still other cases, the pure chemical aspect is covered by section C and the applied chemical aspect by another section, such as A, B or F, e.g., the use of a substance or composition for: treatment of plants or animals, covered by subclass ; foodstuffs, covered by class ; ammunition or explosives, covered by class . When the chemical and mechanical aspects are so closely interlocked that a neat and simple division is not possible, or when certain mechanical processes follow as a natural or logical continuation of a chemical treatment, section C may cover, in addition to the chemical aspect, a part only of the mechanical aspect, e.g., after-treatment of artificial stone, covered by class . In this latter case, a note or a reference is usually given to make the position clear, even if sometimes the division is rather arbitrary. In this subclass, the following terms or expressions are used with the meanings indicated: "use of materials for coating compositions" means the use of known or new polymers or products; "rubber" includes: natural or conjugated diene rubbers; rubber in general (for a specific rubber, other than a natural rubber or a conjugated diene rubber, see the group provided for coating compositions based on such macromolecular compounds); "based on" is defined by means of Note (3), below; "filling pastes" means materials used to fill up the holes or cavities of a substrate in order to smooth its surface prior to coating. In this subclass, coating compositions, containing specific organic macromolecular substances are classified only according to the macromolecular substance, non-macromolecular substances not being taken into account. Example: a coating composition containing polyethene and amino-propyltrimethoxysilane is classified in group . However, coating compositions containing combinations of organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond with prepolymers or polymers other than unsaturated polymers of groups are classified according to the unsaturated non-macromolecular component in group . Example: a coating composition containing polyethene and styrene monomer is classified in group . Aspects relating to the physical nature of the coating compositions or to the effects produced, as defined in group , if clearly and explicitly stated, are also classified in this subclass. Coating compositions characterised by other features, e.g. additives, are classified in group , unless the macromolecular constituent is specified. In this subclass, coating compositions comprising two or more macromolecular constituents are classified according to the macromolecular constituent or constituents present in the highest proportion, i.e. the constituent on which the composition is based. If the composition is based on two or more constituents, present in equal proportions, the composition is classified according to each of these constituents. Example: a coating composition containing 80 parts of polyethene and 20 parts of polyvinylchloride is classified in group . A coating composition containing 40 parts of polyethene and 40 parts of polyvinylchloride is classified in groups and . COATING COMPOSITIONS, e.g. PAINTS, VARNISHES, LACQUERS Based on inorganic substances Based on organic macromolecular substances Based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond Physical nature or effects produced, including use as filling pastes Other features INKS WOODSTAINS CHEMICAL PAINT OR INK REMOVERS CORRECTING FLUIDS PASTES OR SOLIDS FOR COLOURING OR PRINTING Pencil-leads; crayon compositions; chalk compositions Pigment pastes In groups , any macromolecular constituent of a coating composition which is not identified by the classification according to Note (3) after the title of subclass , and the use of which is determined to be novel and non-obvious, must also be classified in a group chosen from groups . Any macromolecular constituent of a coating composition which is not identified by the classification according to Note (3) after the title of subclass or Note (1) above,and which is considered to represent information of interest for search, may also be classified in a group chosen from groups . This can for example be the case when it is considered of interest to enable searching of coating compositions using a combination of classification symbols. Such non-obligatory classification should be given as "additional information." In groups , "aliphatic radical" means an acyclic or a non-aromatic carbocyclic carbon skeleton which is considered to be terminated by every bond to: an element other than carbon; a carbon atom having a double bond to one atom other than carbon; an aromatic carbocyclic ring or a heterocyclic ring. In groups , in the absence of an indication to the contrary, a copolymer is classified according to the major monomeric component. In groups , in the absence of an indication to the contrary, coating compositions based on macromolecular compounds obtained by reactions forming two different linkages in the main chain are classified only according to the linkage present in excess.