SYMBOL_CLASS is an attribute selection that identifies the type of
    symbol. A symbol can be a variable, constant, or some other class.

    The format for SYMBOL_CLASS is as follows:

    SYMBOL_CLASS=(keyword[,keyword...])

    The SYMBOL_CLASS can be one of the following keywords:

    o  ARGUMENT - formal argument (such as a routine argument or macro
       argument)

    o  COMPONENT,FIELD - component of a record

    o  CONSTANT,LITERAL - named compile-time constant value

    o  EXCEPTION - exception

    o  FILE - file

    o  FUNCTION,PROCEDURE, PROGRAM,ROUTINE, SUBROUTINE - callable
       program function

    o  GENERIC - generic unit

    o  KEYWORD - keyword

    o  LABEL - user-specified label

    o  MACRO - macro

    o  MODULE, PACKAGE - collection of logically related elements

    o  PLACEHOLDER - marker where program text is needed

    o  PSECT - program section

    o  TAG - comment heading

    o  TASK - task

    o  TYPE - user-defined type

    o  UNBOUND - unbound name

    o  VARIABLE - program variable

    o  OTHER - any other class of symbol

    The previous keywords are SCA terms. For information on
    corresponding language-specific terms, request help for the
    appropriate language table (for example, FORTRAN_ATTRIBUTES_TABLE)
    under the Getting_Started help topic.

    An example using the SYMBOL_CLASS attribute follows:

      FIND X AND SYMBOL_CLASS=ROUTINE

    This query finds all routines named X.