anchor.diff:         character*30 pname 
   c
          pname = "xyz_read_coords_byname"
  +       c1 = 0.0d0
  +       c2 = 0.0d0
          write(*,*) "in "//pname
          j1 = 0
          j2 = 0
  
positive.code:         read(bigbuf,*,err=137) tag,(c3(k),k=1,3)
  c        
          if(index(tag,atag1(1:len_trim(atag1))).ne.0) then
            j1 = j1+1
            if(j1.gt.n1) goto 138
            c1(j1,:)=c3
          else if(index(tag,atag2(1:len_trim(atag2))).ne.0) then
            j2 = j2+1
            if(j2.gt.n2) goto 138
            c2(j2,:)=c3
          end if
         end do
  135    continue
         n1=j1
         n2=j2
  
negative.code:        integer fn_in
         integer fn_out
         integer n,n1,n2
         double precision dr
         integer nf
         integer nfrm
  c      allocatable arrays
         double precision, dimension(:,:), allocatable :: c
         double precision, dimension(:,:), allocatable :: c1
         double precision, dimension(:,:), allocatable :: c2
         double precision, dimension(:), allocatable :: gr0
         double precision, dimension(:), allocatable :: gr
  c
  c      --------------------------------------------      
  c      beging parsing command line arguments if any
  c      --------------------------------------------      
         nfrm = 0
         aformat = " "
         file_in  = " "
         file_out = " "
  