f more diversified
junk, of which the metal scrap may form one pile, rags another, old
bricks another, old timber another, and, still another, timber having
metal-straps, bolts, nails, etc., connected with it.

_Superiority and inferiority._--In the arrangement of subclasses in a
class, those groups that are related to each other as wholes and parts
are arranged so that the wholes shall stand before the parts, and so
that subclasses defined by effect or by special use shall stand before
those defined by function or general use. For example, in the scrap
illustration above, assuming the titles to be in a printed arrangement,
"chains" precedes "links," which may be parts of chains, and if it had
been desired to separate animal-drags, for instance, from the scrap,
some animal-drags being particular adaptations of a bar, links, and
ball, the group of animal-drags should precede "Bar, link, and ball."
The words "superior" and "inferior" have been used to indicate this
relationship. A class or subclass defined to receive a certain
combination is superior to one defined to receive an element or a
combination that is a part of that certain combination. A class or
subclass defined to receive means for making a particular product, as an
electric lamp, is superior to a class or subclass designed to perform a
general function, as pumping air from a container. And whenever a
question of assignment of a patent or application that contains matters
of two or more groups bearing that relation is raised, the "superior"
group is selected to receive it.

Further, in those instances in which groups are formed on different
bases or different characteristics, not comparable with each other, and
a patent is presented having matter falling in each group, that group
which is highest in position is preferred in those instances where
separate provision for means having both characteristics has not been
made.

In cases of necessity, as where a combination is presented for which no
class has been definitely provided, but classes exist into which the
several parts would fall if separately claimed, the same practice that
obtains in similar situations with respect to two or more _subclasses_
of a class may be followed with respect to two or more _classes_ and the
patent placed in that class which, in accordance with above-stated
principles, should be deemed the "superior."

_Definite positional relationship of subdivisions._--In the metal scrap
ex