anchor.diff:        if(icode.eq.7) idam=3
         if(ilapa.ne.ifipa) then !Is first particle != Last particle?
           ntwin=2               !(ntwin=1 is the default in postpr)
  -!--   binrecs is indexed as 1,2,3,... (=i.e.(91-nfile) in the non-STF version,
   !--   while posi values are called as 1,3,5, so using posi1 for crbinrecs index later
         endif
         posi1 = (posi+1)/2 !For both ntwin=1 and 2
  -#endif
  -
  -#ifndef STF
  -!--PREVENT FAULTY POST-PROCESSING
  -      read(nfile,end=530,iostat=ierro) iaa
  -
  -      if(ierro.gt.0) then
  -        write(lout,10320) nfile
  -        goto 550
  -      endif
  -
  -      read(nfile,end=535,iostat=ierro) iab
  -
  -      if(ierro.gt.0) then
  -        write(lout,10320) nfile
  -        goto 550
  -      endif
  -#else
  +
   !--PREVENT FAULTY POST-PROCESSING
         !--bypass headers
         rewind nfile
  
positive.code:         write(lout,10320) nfile
          goto 550
        endif
  #endif
  
        if((((numl+1)/iskip)/(iab-iaa))/iav.gt.nlya) nstop=iav*nlya
  
        rewind nfile
  
  !-- Bypassing header to read tracking data later
  #ifndef STF
        read(nfile)
  #else
        do i=1,itopa,2
           read(nfile) !One header per particle pair.
        enddo
  #endif
        sumda(5)=ta(1,1)**2+ta(1,2)**2
        sumda(6)=ta(3,3)**2+ta(3,4)**2
  
  
negative.code: !----------------------------------------------------------------------
        rewind nfile
        ia=0
        !Read header lines until a match is found
   555  continue
        read(nfile,end=510,iostat=ierro) &
  