subroutine limons (root, limmo)

      character*(*) root
      integer limmo(2)

c find the range of months present

      character*60 filnam
      integer lenam, iymo, nextmo, mold
      integer*2 iyr, imon, iday

      limmo(1) = 0
      limmo(2) = 0

c pick up current date

      call getdat (iyr, imon, iday)
      iymo = iyr*100 + imon

c go backwards from current month looking for last month on CDrom

c old line :-
c      do while (limmo(2) .eq. 0 .and. iymo .gt. 196000)

c Modified July 16th 2003 - Peter - enables iscbul to work on a
c subset of data and NOT just from 1960+ - backwards

      do while (limmo(2) .eq. 0 .and. iymo .gt. 190000)

        call monfil (iymo, root, filnam, lenam)
        
        if (lenam .eq. 0) then
          iymo = nextmo (iymo, -1)
        else
          limmo(2) = iymo
        end if
      end do

      if (limmo(2) .ne. 0) then

c now find first month present

c July 16th 2003 Peter - existing code stopped when hit a
c non-existent month EVEN though there could be earlier
c months

c old line :-
c        do while (limmo(1) .eq. 0)

         do while (iymo .gt. 190000) 
        
          call monfil (iymo, root, filnam, lenam)
          
          if (lenam .ne. 0) then
            mold = iymo
            
c old line moved to end of 'end if'
c            iymo = nextmo (iymo, -1)

          else
            limmo(1) = mold
          end if
          iymo = nextmo (iymo, -1)
          
        end do
        
      end if
      return
      end