subroutine diftmsr (iyd1,it1,iyd2,it2,iflag,idms)
c
c computes t1-t2 and gives the difference in millisecs
c
c ------------------------------------------------------
c beware no check at year boundaries yet !!!
c ------------------------------------------------------
c
c v1.0 jfe johnson 30 oct 81
c v1.1 jfej         1 nov 81
c
      integer*4 iflag
      real*8 iyd1,it1,iyd2,it2,idms,id
c
c compute differences in time
c
      id=iyd1-iyd2
      iflag=1
      idms=0
      if(dabs(id).gt.1.0d0)return
      idms=it1-it2+id*86400000000.0d0
      iflag=0
      if(dabs(idms).lt.86400000000.0d0)return
      iflag=1
      idms=0
      return
      end