SKRHEX    SKRHEX    SKRHEX    SKRHEX    SKRHEX    SKRHEX    SKRHEX    
          **********************************************
                    **************************
                              ******

SUBROUTINE SKRHEX (K, ISKWRK, RSKWRK, A6)

Returns an array of the sixth thermodynamic polynomial
coefficients for a species, or changes their value,
depending on the sign of K.

INPUT
K         - Integer scalar, species index;
            K > 0 gets A6(*) from RSKWRK
            K < 0 puts A6(*) into RSKWRK
ISKWRK(*) - Integer workspace array; dimension at least LENISK.
RSKWRK(*) - Real    workspace array; dimension at least LENRSK.

If K < 0:
A6(*)     - Integer array, the 6th thermodynamic polynomial
            coefficients for species K, over the number of
            temperature ranges used in fitting thermodynamic
            properties;
            dimension at least MAXTP-1, where MAXTP is the
            maximum number of temperatures used in fitting the
            thermodynamic properties of the species.

OUTPUT
If K > 0:
A6(*)     - Integer array, the 6th thermodynamic polynomial
            coefficients for species K, over the number of
            temperature ranges used in fitting thermodynamic
            properties;
            dimension at least MAXTP-1, where MAXTP is the
            maximum number of temperatures used in fitting the
            thermodynamic properties of the species.