subroutine addtm2 (iyd1, it1, inc, iyd2, it2)
c
c-----------------------------------------------------------------------
c
c Adds a positive increment inc (in ms) to the time in iyd1, it1
c
c-----------------------------------------------------------------------
c
      integer*4 idy2, inc, it1, it2, iyd1, iyd2, iyr2, leap
c
c-----------------------------------------------------------------------
c     *** parse the year and day of year ***
c-----------------------------------------------------------------------
c
      iyr2 = iyd1 / 1000
      idy2 = iyd1 - (iyr2 * 1000)
c
c-----------------------------------------------------------------------
c     *** check for leap year, RIMS requires only the simple test ***
c-----------------------------------------------------------------------
c
      leap = 0
      if (mod(iyr2, 4) .eq. 0) leap = 1
c
c-----------------------------------------------------------------------
c     *** increment the time ***
c-----------------------------------------------------------------------
c
      it2 = it1 + inc
c
c-----------------------------------------------------------------------
c     *** check for day crossing and year crossing ***
c-----------------------------------------------------------------------
c
      if (it2 .ge. 86400000) then
         it2 = it2 - 86400000
         idy2 = idy2 + 1
         if (leap .eq. 0) then
            if (idy2 .gt. 365) then
               idy2 = idy2 - 365
               iyr2 = iyr2 + 1
            end if
         else
            if (idy2 .gt. 366) then
               idy2 = idy2 - 366
               iyr2 = iyr2 + 1
            end if
         end if
      end if
c
c-----------------------------------------------------------------------
c     *** rebuild year and day of year combined variable ***
c-----------------------------------------------------------------------
c
      iyd2 = (iyr2 * 1000) + idy2
c
c-----------------------------------------------------------------------
c-----------------------------------------------------------------------
c
      return
      end