anchor.diff:    end function numSTFpairs
   
     subroutine convertSTFpair(pairIdx, ifname, ofname)
  +
       integer, intent(in)          :: pairIdx !Which pair to extract
       character(len=*), intent(in) :: ifname  !Name of the singletrackfile to split
       character(len=*), intent(in) :: ofname  !Name of the output file
   
       integer iostat
  -
       integer iPair
  +    double precision, parameter :: zero = 0.0d0
   
       open(unit=inUnit,  file=ifname, form='UNFORMATTED', status='OLD',     action='READ',  err=410, iostat=iostat)
       open(unit=outUnit, file=ofname, form='UNFORMATTED', status='REPLACE', action='WRITE', err=411, iostat=iostat)
  
positive.code:              ta(3,3),ta(3,4),ta(3,5),ta(3,6), ta(4,1),ta(4,2),ta(4,3),ta(4,4), &
               ta(4,5),ta(4,6), ta(5,1),ta(5,2),ta(5,3),ta(5,4),ta(5,5),ta(5,6), &
               ta(6,1),ta(6,2),ta(6,3),ta(6,4),ta(6,5),ta(6,6), dmmac,dnms,dizu0,&
               dnumlr,sigcor,dpscor
  
          ntwin = ilapa-ifipa+1
          if (.not. (ntwin == 1 .or. ntwin == 2)) then
  
negative.code: module mod_splitSingletrack
  
    use iso_fortran_env, only : output_unit
  
    implicit none
  
    ! File units used for I/O;
  