SUBROUTINE SPSIGK(ITR,IB,FR,SIGSP)
C     ==================================
C
C     Non-standard evaluation of the photoionization cross-sections
C     Basically user-suppled procedure; here are some examples
C
      INCLUDE 'PARAMS.FOR'
      SIGSP=0.
      if(itr.le.0) return
C
C     Special formula for the He I ground state
C
      IF(IB.EQ.-201) SIGSP=7.3E-18*EXP(1.373-2.311E-16*FR)
C
C     Special formula for the averaged <n=2> level of He I
C
      IF(IB.EQ.-202) SIGSP=SGHE12(FR)
C
C     Carbon ground configuration levels 2p2 1D and 1S
C
      IF(IB.EQ.-602.OR.IB.EQ.-603) THEN
         CALL CARBON(IB,FR,SG)
         SIGSP=SG
      END IF
C
C     Hidalgo (Ap.J. 153, 981, 1968) photoionization data
C
      IF(IB.LE.-101.AND.IB.GE.-137) SIGSP=HIDALG(IB,FR)
C
C     Reilman and Manson (Ap.J. Suppl. 40, 815, 1979) photoionization data
C
      IF(IB.LE.-301.AND.IB.GE.-337) SIGSP=REIMAN(IB,FR)
      RETURN
      END