Name:       GDS___CHECK

Purpose:    Condition checking and handling routine

Author:     J.P. Terlouw

Use:        CALL GDS___CHECK ( cond, code, error, exit )

                 cond   =   logical expression
                 code   =   INTEGER variable, constant or
                            expression
                 error  =   INTEGER variable containing the
                            error argument as declared
                 exit   =   any of the following specifiers:
                            *RETURN, *XWHILE, *XREPEAT, *XFOR or
                            *procedurename

Description:
            If 'error' < 0 , this routine calls GDS___ERROR with this
            value and does no further checking.
            If 'error' >= 0, or if 'error' has not been specified in
            the call to the routine which calls this one, the following
            procedure is followed:
            If the condition 'cond' is .TRUE., this routine does nothing.
            If it is .FALSE., and 'error' has been specified in the call
            to the subroutine which calls GDS___CHECK, then 'code' is
            copied to 'error' and the statement specified in 'exit' is
            executed; if 'error' has not been specified, then GDS___CHECK
            calls GDS___ERROR with 'code' as argument.

Note:       This routine is not C-compatible .

Update history:
            1-Apr-87    Original document
           15-Dec-89    version compliant with GPS