subroutine diftms (iyd1, it1, iyd2, it2, iflag, idms)
c
c-----------------------------------------------------------------------
c
c     Computes t1-t2 and gives the difference in millisecs.
c
c     If the time difference is greater than 1(one) day then iflag = 1
c     and idms = 0.
c
c-----------------------------------------------------------------------
c
c-----------------------------------------------------------------------
c ------------------------------------------------------
c beware no check at year boundaries yet !!!
c ------------------------------------------------------
c-----------------------------------------------------------------------
c
      integer*4 idms, iflag, it1, it2, iyd1, iyd2
c
c-----------------------------------------------------------------------
c-----------------------------------------------------------------------
c
      id = iyd1 - iyd2
      iflag = 1
      idms = 0
      if (iabs(id) .gt. 1) return
c
c-----------------------------------------------------------------------
c-----------------------------------------------------------------------
c
      idms = it1 - it2 + (id * 86400000)
      iflag = 0
      if (iabs(idms) .lt. 86400000) return
c
c-----------------------------------------------------------------------
c-----------------------------------------------------------------------
c
      iflag = 1
      idms = 0
c
c-----------------------------------------------------------------------
c-----------------------------------------------------------------------
c
      return
      end