Any object in a program. For example, a FUNCTION, a VARIABLE, a
    CONSTANT, or any of the entities with which a programmer typically
    deals.

    A symbol has occurrences. For example, the declaration of
    a variable is an occurrence, and uses of the variable are
    occurrences. SCA determines which occurrences belong to which
    symbols using the rules of the language you are using. For
    example, you may have two different variables named INDEX in
    separate subroutines. According to the rules of your language,
    these are usually different variables, so they are different
    symbols for SCA.

    It does not matter whether all occurrences of a symbol are in
    a single compilation unit, or spread over several compilation
    units. All the occurrences still belong to the same symbol. For
    example, you may have a subroutine SUB1 in one module, and calls
    to that subroutine in several other modules. These all appear as
    occurrences of the same symbol, named SUB1.

    The programmer and SCA should have the same definition of what
    constitutes a unique item. SCA's term for a unique item is symbol.