anchor.diff:    character(len=long_string_size) :: syntax = 'syntax'
     character(len=long_string_size) :: rst_file
     integer :: iv,jv,is,js,k
  +  integer :: n_digits = -1
     character(len=1) :: protein_alphabet(21) = &
          ['A','C','D','E','F','G','H','I','K',&
          'L','M','N','P','Q','R','S','T','V','W','Y','-']
     character(len=1) :: nuc_acid_alphabet(6) = &
          ['A','C','G','T','U','-']
  +  character(len=long_string_size) :: frmt
     
     ! read arguments
     call get_command(cmd)
  
positive.code:      end do
    end if
    k = 0
    do iv = 1,nvars
       do is = 1,nclasses
          k = k + 1
          write(*,'(i3,1x,i2,1x,f8.4)') iv,is,prm(k)
       end do
    end do
    do jv = 1,nvars-1
       do iv = jv+1,nvars
          do js = 1,nclasses
             do is = 1,nclasses
                k = k + 1
                ! order is inverted for printing 
                write(*,'(2(i3,1x),2(i2,1x),f8.4)') jv,iv,js,is,prm(k)
             end do
          end do
       end do
    end do
  
  
negative.code:         stop
       end select
    end do args_loop
  
    write(frmt,*) 
  
    call units_open_unf(rst_file,'old',unt,err)
    
  