SKKUW     SKKUW     SKKUW     SKKUW     SKKUW     SKKUW     SKKUW     
          **********************************************
                    **************************
                              ******

SUBROUTINE SKKUW (ISKWRK, KWUSR)
Returns a set of flags indicating whether the species are
user-modify rate-of-production species, and if so,
the user-modify type.

INPUT
ISKWRK(*) - Integer workspace array; dimension at least LENISK.
OUTPUT
KWUSR(*)  - Integer array, user rate-modify flags for species;
            dimension at least KKTOT, the total species count.
            KWUSR(K)= 0  species K is not a user rate-modify species
            KWUSR(K)= N  species is a user rate-modify species,
                         with rate-modify type N