anchor.diff:         character*(180) buffer
          character*(180) message
          integer istatus
  -       logical overb,ohelp
  +       logical overb,ohelp,odistinct
          character*255 file_lattice,file_in,file_out
          character*16 atom1_tag
          character*16 atom2_tag
  
positive.code:          if(n.eq.0) exit
           write(*,*) "number of atoms", n
           oc1=.false.
           if(atom1_id.gt.0) then
             oc1=.false.
             oc1(atom1_id) = .true.
           else if(atom1_tag.ne." ") then
             oc1 = atag.eq.atom1_tag
  c           call mask_byname(n,c,atag,oc1,atom1_tag)
           end if
           oc2=.false.
           if(atom2_id.gt.0) then
             oc2(atom2_id) = .true.
           else if(atom2_tag.ne." ") then
             oc2 = (atag.eq.atom2_tag).and.(.not.oc1)
  c           call mask_byname(n,c,atag,oc2,atom2_tag)
           else
             oc2=oc1
           end if
           gr0 = 0
           call rdf_compute2(n,c,oc1,oc2,
       +                    nb,rmax,lat,
  
negative.code:             end if
            end do
  c          write(*,*) "done reading lattice"
            go to 16
         else if(buffer.eq."-nodistinct") then
            odistinct=.false.
            go to 16
         else if(buffer.eq."-distinct") then
            odistinct=.true.
            go to 16
         else if(buffer.eq."-v") then
            overb=.true.
  