anchor.diff:          call json_write_key(js, 'density_matrices', ccmc%density_matrices)
           call json_write_key(js, 'density_matrix_file', ccmc%density_matrix_file)
           call json_write_key(js, 'even_selection', ccmc%even_selection)
  +        call json_write_key(js, 'multiref', ccmc%multiref)
           if (ccmc%multiref) then
  +            call json_write_key(js, 'n_secondary_ref', ccmc%n_secondary_ref)
               call json_write_key(js, 'mr_read_in', ccmc%mr_read_in)
  -            call json_write_key(js, 'n_secondary_ref', ccmc%n_secondary_ref)
  -            if (ccmc%n_secondary_ref .le. 20 .and. .not. ccmc%mr_read_in) then
  +            if (.not. ccmc%mr_read_in) then
                   do i=1, size(ccmc%secondary_refs)
                       write (string, '(A13,I0)') 'secondary_ref', i
  -                    call reference_t_json(js, ccmc%secondary_refs(i), key = trim(string))
  +                    call reference_t_json(js, ccmc%secondary_refs(i), key=trim(string))
                   end do
  -            else if (ccmc%mr_read_in) then
  +            else
                   call json_write_key(js, 'sym_only', ccmc%mr_secref_sym_only)
  -            else
  -                call warning('ccmc_in_t_json','There are more than 20 secondary references, &
  -                &printing suppressed, consider using the mr_read_in functionality.')
  +                call json_write_key(js, 'mr_secref_file', ccmc%mr_secref_file)
  +                call json_write_key(js, 'secref_bit_string_len', ccmc%secref_bit_string_len)
  +                call json_write_key(js, 'mr_n_frozen', ccmc%mr_n_frozen)
               end if
               select case (ccmc%mr_acceptance_search)
               case (0)
  
positive.code:             case (1)
                  call json_write_key(js, 'mr_acceptance_search', 'bk_tree')
              end select
  
              call json_write_key(js, 'mr_secref_file', ccmc%mr_secref_file)
              call json_write_key(js, 'secref_bit_string_len', ccmc%secref_bit_string_len)
              call json_write_key(js, 'mr_excit_lvl', ccmc%mr_excit_lvl)
              call json_write_key(js, 'mr_n_frozen', ccmc%mr_n_frozen)
          end if
          call json_write_key(js, 'multiref', ccmc%multiref, terminal=.true.)
          call json_object_end(js, terminal)
  
      end subroutine ccmc_in_t_json
  
negative.code:     ! Acceptance algorithm for mrcc excitations.
      integer :: mr_acceptance_search
      ! Name of the file containing secondary references (only if mr_read_in is true).
      character(255) :: mr_secref_file = 'secref'
      ! The bit string length used in the secondary reference file. 
      ! This enables reading in references with more than 64 basis functions.
      integer :: secref_bit_string_len
  