CKIREV    CKIREV    CKIREV    CKIREV    CKIREV    CKIREV    CKIREV    
          **********************************************
                    **************************
                              ******

SUBROUTINE CKIREV (IR, ICKWRK, RCKWRK, IREV, RAR, RBR, RER)
Returns an integer flag to indicate whether reaction IR has an
explicitly assigned reverse rate constant.  It also returns the
reverse Arrhenius expression values for reaction IR,
if it was explicitly assigned in the Chemkin interpreter.
If reverse Arrhenius values were not explicitly assigned,
RAR, RBR and RER will be zero.

INPUT
IR        - Integer scalar, reaction index.
ICKWRK(*) - Integer workspace array; dimension at least LENICK.
RCKWRK(*) - Real workspace array; dimension at least LENRCK.

OUTPUT
IREV      - Integer scalar,
            1, reaction IR has explicit reverse rate parameters
            0, no.
RAR       - Real scalar, explicit pre-exponential constants
            for reaction IR.
               cgs units, mole-cm-sec-K
RBR       - Real scalar, explicit temperature dependence exponents
            for reaction IR.
RER       - Real scalar, explicit activation energy for reaction IR.
               cgs units, Kelvins