anchor.diff:      ! 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
  +    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
  
positive.code:         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)
          if (ccmc%multiref) then
              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
                  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))
                  end do
              else if (ccmc%mr_read_in) then
                  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.')
              end if
              select case (ccmc%mr_acceptance_search)
              case (0)
  
negative.code:             case (1)
                  call json_write_key(js, 'mr_acceptance_search', 'bk_tree')
              end select
              
              call json_write_key(js, 'mr_excit_lvl', ccmc%mr_excit_lvl)
          end if
          call json_write_key(js, 'discard_threshold', ccmc%discard_threshold, terminal=.true.)
          call json_object_end(js, terminal)
  
      end subroutine ccmc_in_t_json
  