symbol

    A formal argument that is successively replaced with the
    specified actual arguments enclosed in angle brackets (<>).  If
    no formal argument is specified, the assembler displays an error
    message.

 <argument list>

    A list of actual arguments enclosed in angle brackets and used
    in expanding the indefinite repeat range. An actual argument
    can consist of one or more characters. Multiple arguments must
    be separated by a legal separator (comma, space, or tab). If no
    actual arguments are specified, no action is taken.

 range

    The block of source text to be repeated once for each occurrence
    of an actual argument in the list. The range can contain macro
    definitions and repeat ranges. .MEXIT is legal within the range
    and causes the current and remaining repetitions to be aborted.