CALL SEQUENCE...
       veint    XIN XOUT INPUT OUTPUT \
             [ -kind VAL1 [ VAL2 ] -scal VAL3 -l VAL4 -a VAL5 -c VAL6 ]
 
 
      DESCRIPTION...
       veint  - VERTICAL ETA INTEGRAL FOR DATA ON ETA COORDINATES
 
 
      AUTHOR  - D. LIU (BASED ON VSINTH BY R. LAPRISE), Dec 06/1993.
      LAST REVISION: $Header: Corrections-to-the-detection-of-vertical-intervals-and-a-few-other-minor-changes @ Tue, 21 Mar 2017 14:40:48 -0400 (Bernard Dugas) $
 
 
      PURPOSE - COMPUTES THE VERTICAL ETA INTEGRAL FOR DATA ON ETA
                COORDINATES.
 
      NOTE    - SPECTRAL FIELDS CAN NOT BE HANDLED IN ETA COORD.
 
 
      INPUT FILE...
       XIN    = INPUT SERIES OF ETA LEVEL GRID FIELDS .
 
 
      OUTPUT FILE...
       XOUT   = OUTPUT SERIES OF VERTICAL ETA INTEGRALS OF XIN.
 
 
      INPUT PARAMETERS...
 
       COORD  (kind 1) = 'ETA' OR BLANK FOR ETA LEVELS OF INPUT FIELDS
       LEVTYP (kind 2) = FULL FOR MOMENTUM VARIABLE, AND
                         HALF FOR THERMODYNAMIC ONE.
       CONST  (scal)   = SCALES THE OUTPUT FIELD.
       LAY    (l)      = DEFINES THE POSITION OF LAYER INTERFACES IN
                         RELATION TO LAYER CENTRES (SEE BASCAL; ZERO
                         DEFAULTS TO THE FORMER STAGGERING CONVENTION).
       SIGTOP (a)      = KEPT FOR BACKWARD COMPATIBILITY (NO LONGER USED).
       PTOIT  (c)      = PRESSURE (PA) OF THE RIGID LID OF THE MODEL.
 
       Notes:   1) LAY and LEVTYP define the type of levelling
                   for the variable.
                2) The defaults are as specified in the example below.
 
       READ(5,5010) LEVTYP,CONST,LAY,COORD,SIGTOP,PTOIT
 5010  FORMAT(11X,A4,E10.0,I5,1X,A4,E5.0,E10.0)
 
 
 EXAMPLE OF INPUT CARD...
 
 *VEINT    HALF 10.197671    3  ETA-1.00      0.01
 
         0123456789012345678901234567890123456789012345678901234567890
         1         2         3         4         5         6         7
 
 
      EXIT CONDITIONS...
        0 NO PROBLEMS
        1 UNSUPPORTED VERTICAL COORDINATE
        2 NOT ENOUGH OR TOO MANY LEVELS IN FIRST
          SET OF XIN; OR PREMATURE EOF ON XIN
        3 CANNOT TREAT SPECTRAL ETA LEVELS    
        4 UNSUPPORTED LEVEL TYPE
        5 UNABLE TO READ XIN SET
        6 MORE THAN ONE SIZE IN XIN
        7 PREMATURE EOF ON INPUT
        8 XIN DOES NOT CONTAIN ETA LEVELS