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a.
Class Characteristics Result from a Controlled 
Generation Process
Class characteristics always originate as a result of some repetitive generation
process. This process can be either mechanical or biological. Because the
 
Class Characteristics:
Traits that are produced by a controlled process. 
They are used to group like objects into sets.
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Classification, Identification, and Individualization
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production of the material is controlled either by nature or by humans, all
items that originate as a result of this process will exhibit the same class
characteristics. Cocaine produced in coca plants, shoes manufactured from
a mold in a shoe plant, and gross rifling characteristics in the barrels of a
particular make and model of gun, all result from processes that produce
more than one item with similar traits. As they are produced or manufac-
tured, they are indistinguishable by the traits conferred by that process. For
instance, the cocaine molecules from all coca plants are easily identified as
cocaine by their chemical structure; the shoes from a single mold can all be
traced by their tread pattern, including any defects in the mold; and the gross
rifling characteristics of a gun barrel derive directly from the tool and process
used to imprint them. These reproducible traits are exploited by the analyst
to classify objects and substances in the laboratory.
Scale of detection imposes an unavoidable limit on the reproducibility
of class characteristics. Even items produced by the same process can be
distinguished by microcharacteristics if one looks closely enough. By their
nature, microcharacteristics cannot be controlled because they result from
random events. These fortuitous differences in manufacture or generation
are one source of the individualizing characteristics that we discuss later in
this chapter. Examples include differences in the microstriae of consecutively
manufactured gun barrels, bubble formation in polyurethane-blown shoe
molds, and mutations during DNA replication that might produce mutant
cocaine molecules.