The basic elements through which artifacts are compared. Comparison of two features always yields a binary {0, 1} outcome indicating a match or non-match; because features are defined as the most basic comparison unit that the algorithm considers, partial matches are not permitted. Generally, a feature can be any value derived from an artifact. Each approximate matching algorithm must define the structure of its features and the method by which they are derived. For example, an algorithm might define a feature as a (byte, offset) pair produced by reading the value of a byte and storing it along with the offset at which it was read.
Source(s):
NIST SP 800-168