anchor.diff:      type(hash_table_t) :: ht
   end type rdm_spawn_t
   
  -! [todo] - move to dmqmc_state_t
   ! This type contains information for the RDM corresponding to a given
   ! subsystem. It takes translational symmetry into account by storing information
   ! for all subsystems which are equivalent by translational symmetry.
  
positive.code: 
  end type dmqmc_rdm_in_t
  
  ! [todo] - move to dmqmc_state_t
  ! Spawned lists for rdms.
  type rdm_spawn_t
      type(spawn_t) :: spawn
  
negative.code:     ! are reset on each processor to start the next report loop.
      real(p), allocatable :: estimator_numerators(:) !(number_dmqmc_estimators)
  
      ! This array is used to hold the number of particles on each excitation
      ! level of the density matrix.
      real(p), allocatable :: excit_distribution(:) ! (0:max_number_excitations)
  
      ! [todo] - (NSB) remove these two - I doubt they'll ever be used.
  