Material which is used to form a visible record comprising plural leaves so associated that the bottom surface of a top leaf, so as to produce a mark, usually upon the application of pressure in a direction normal to the plane of the leaves.
(1) Note. The interaction may comprise any chemical or physical phenomenon and is usually dependent upon the complementarity of the composition or physical characteristics of the facing surfaces; in the usual case a frangible transfer surface on one sheet mates with the adhesive surface of a receiver sheet.
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200, for similar subject matter where one of the said surfaces provides a colorless color-forming material for development by a reactant material in said other surface.
