anchor.diff:  
     SUBROUTINE interpolate_CAMgases(yr, julian, yeari, juli, yr1, yr2, yearf, julf, gas, interp_gas)
       IMPLICIT NONE
  -! These subroutine interpolates a trace gas concentration from a non-homogeneously 
  +! These subroutine interpolates a trace gas concentration from a non-homogeneously
   ! distributed gas concentration evolution
       INTEGER, INTENT (IN)                      :: yr, yeari, yr1, yr2, yearf, juli, julf
       REAL, INTENT (IN)                         :: julian
  
positive.code:   PUBLIC :: read_CAMgases
  
  CONTAINS
    
    SUBROUTINE read_CAMgases(yr, julian, model, co2vmr, n2ovmr, ch4vmr, cfc11vmr, cfc12vmr) 
      USE io_routines , ONLY: io_newunit
      INTEGER, INTENT(IN)            :: yr
      REAL, INTENT(IN)               :: julian
  
negative.code:        ENDIF
         iyear=iyear+1
      ENDDO
  
      ! Prevent yr > last year in data
  !    IF (yearIN .ge. VARCAM_in_years) yearIN=VARCAM_in_years-1
      IF (iyear .ge. max_years) then
         yearIN=max_years-1
         found_yearIN = 1
      ENDIF
  
      IF (found_yearIN .NE. 0 ) THEN
         if (yearIN .eq. 1) yearIN = yearIN + 1    ! To take 2 first lines of the file
         nyrm = yrdata(yearIN-1)
  