CALL SEQUENCE...
      diftim  XIN XOUT INPUT OUTPUT [-name "VAL1" -t1 VAL2   -t2 VAl3
                                                  -t3 VAL4 -kind VAL5 ]
 
 
      DESCRIPTION...
      diftim  - DIFFERENCE OF TWO SETS IN THE SAME FILE (CAN DIV BY DT)
 
 
      AUTHOR  - J.D.Henderson, 1981.
      LAST REVISION: $Header: /home/cvs/RMNLIB/utils/rdiag/lspgm/diftim.ptn,v 4.12 2014/09/25 20:20:47 dugas Exp $
 
 
      PURPOSE - SUBTRACTS TWO SETS IN A FILE XIN AS SELECTED ON A CARD AND
                OPTIONALLY DIVIDES BY THE TIME DIFFERENCE BETWEEN THEM.
 
 
      INPUT FILE...
       XIN = FILE OF MULTI-LEVEL SETS (REAL OR COMPLEX)
 
      OUTPUT FILE...
       XOUT = ONE SET WHICH IS THE DIFFERENCE BETWEEN THE TWO SPECIFIED
              INPUT SETS.
 
 
      INPUT PARAMETERS...
 
       NAME    = NAME OF THE FIELDS. IF NONE IS SPECIFIED, 
                 THE FIRST ONE FOUND IS USED.
       NT1,NT2 = FIRST AND SECOND TIMESTEP NUMBERS.
       (t1,t2)   DATA AT TIME NT1 IS SUBTRACTED FROM TIME NT2.
                 A) NT2 MAY BE LESS THAN NT1 IF REQUIRED.
                 B) WHEN NT1 OR NT2 ARE NOT TIMESTEPS NUMBER OF
                    THE FILE,  THE NEAREST TIMESTEPS WITHIN THE PERIOD
                    NT1 TO NT2 ARE USED.
                 C) WHEN 'NT1.LT.0', ALL TIMESTEPS ARE CONSIDERED AND
                    NT2 IS DISREGARDED.
                 D) WHEN BOTH NT1,NT2 = 0, ALL TIMESTEPS ARE CONSIDERED
       DT      = NUMBER OF SECONDS BETWEEN SUCESSIVE TIMESTEPS IN THE FI
       (t3)      (IF DT=0. NO TIME DIFFERENCE DIVISION IS DONE)
       TCFLAG  = > 0, CCCma TIME CODE FLAG: IF TCFLAG=1, THE TIMESTEP IS
       (kind)         ASSUMED TO BE OF THE FORM YYYYMMDDHH, ANY OTHER VALUE
                      INDICATES THAT THE TIMESTEP IS INDEED JUST THAT.
                      NOTE THAT A RPN STANDARD FILE DOES NOT NORMALLY USE
                      THE NT1,NT2 AND DT VALUES, AS THESE ARE INCLUDED
                      IN THE FILE ITSELF. NTI AND NT2 ARE THEN THE EARLIEST
                      AND LATEST TIMES IN THE FILE.
                 < 0, INDICATES THAT RPN FILES WILL USE THE NT1,NT2 AND
                      DT VALUES, AS WELL AS THE ABSOLUTE VALUE OF TCFLAG.
                 
 
       READ( 5,5010 ) NAME,NT1,NT2,DT,TCFLAG
  5010 FORMAT(10X,1X,A4,2I10,2F10.0)
 
 
      EXAMPLE OF INPUT CARD...
 
  DIFTIM    PCP         0        72     1800.
 
         0123456789012345678901234567890123456789012345678901234567890
         1         2         3         4         5         6         7
 
 
      EXIT CONDITIONS...
        0 NO PROBLEMS
        1 PROBLEMS READING FIRST SET AT OR AFTER NT1
        2 FIRST SET SEEMS INCOMPLETE
        3 PROBLEMS READING LAST SET AT OR BEFORE NT2
        4 ERROR ABORT READING INPUT
        5 MORE THAN ONE TYPE OF DATA IN XIN