In using any classification system, it is necessary to analyze the organization of the class or classes to be included in the search.
The initial analysis should determine which one or ones of the several types of subject matter (manufacture, art, apparatus, or stock material) are contained in the class being considered.
Further, relative to each type of subject matter, it is necessary to consider each of the various combinations and subcombinations set out below:
Basic Subject Matter Combined with Feature for Some Additional Purpose. The added purpose is in excess of the scope of the subject matter for the class, as defined in the class definition; e.g., adding a sifter to a stone crusher which gives the added function of separating the crushed stone.
Basic Subject Matter Combined with Perfecting Feature. Features may be added to the basic subject matter which do not change the character thereof, but do perfect it for its intended purpose; e.g., an overload release means tends to perfect a stonecrusher by providing means to stop it on overload and thus prevent ruining the machine. However, this perfecting combined feature adds nothing to the basic character of the machine.
Basic Subject Matter. The combination of features necessary and essential to the fundamental character of the subject matter treated; e.g., a stonecrusher requires a minimum number of features as essential before it can function as such.
Subcombinations Specialized to Basic Subject Matter. Each type of basic subject matter may have subcombinations specialized to use therewith; e.g., the crushing element of a stonecrusher.
Subcombinations of General Utility. Each type of basic subject matter may have subcombinations which have utility with other and different types of subject matter; e.g., the machine elements of a stonecrusher. Subcombinations of this character usually are provided for in some general class so that the examiner should determine in each instance where they are classified.