anchor.diff:         IN_TOP    = 5,   &
          OUT_TOP   = 6
   
  -  ! Fission neutron emission (nu) type
  +  ! ============================================================================
  +  ! MISCELLANEOUS CONSTANTS
  +
  +  ! Codes for read errors -- better hope these numbers are never used in an
  +  ! input file!
  +  integer, parameter :: ERROR_INT  = -huge(0)
  +  real(8), parameter :: ERROR_REAL = -huge(0.0_8) * 0.917826354_8
  +
  +  ! Source types
     integer, parameter ::   &
  -       NU_NONE       = 0, & ! No nu values (non-fissionable)
  -       NU_POLYNOMIAL = 1, & ! Nu values given by polynomial
  -       NU_TABULAR    = 2    ! Nu values given by tabular distribution
  -
  -  ! Cross section filetypes
  -  integer, parameter :: &
  -       ASCII  = 1, & ! ASCII cross section file
  -       BINARY = 2    ! Binary cross section file
  -
  -  ! Maximum number of partial fission reactions
  -  integer, parameter :: PARTIAL_FISSION_MAX = 4
  -
  -  ! Maximum number of words in a single line, length of line, and length of
  -  ! single word
  -  integer, parameter :: MAX_WORDS    = 500
  -  integer, parameter :: MAX_LINE_LEN = 250
  -  integer, parameter :: MAX_WORD_LEN = 150
  -  integer, parameter :: MAX_FILE_LEN = 255
  +       SRC_BOX     = 1, & ! Source in a rectangular prism
  +       SRC_CELL    = 2, & ! Source in a cell
  +       SRC_SURFACE = 3    ! Source on a surface
  +
  +  integer, parameter ::        &
  +       PROB_SOURCE      = 1, & ! External source problem
  +       PROB_CRITICALITY = 2    ! Criticality problem
   
     ! Unit numbers
     integer, parameter :: UNIT_LOG   = 11 ! unit # for writing log file
  
positive.code:        & SENSE_POSITIVE = 1, &
         & SENSE_NEGATIVE = -1
  
    ! Used for surface current tallies
    real(8), parameter :: TINY_BIT = 1e-8
  
    ! Maximum number of collisions/crossings
    integer, parameter :: MAX_EVENTS = 10000
    integer, parameter :: MAX_SAMPLE = 100000
  
    ! Codes for read errors -- better hope these numbers are never used in an
    ! input file!
    integer, parameter :: ERROR_INT  = -huge(0)
    real(8), parameter :: ERROR_REAL = -huge(0.0_8) * 0.917826354_8
  
    ! Source types
    integer, parameter ::   &
         SRC_BOX     = 1, & ! Source in a rectangular prism
         SRC_CELL    = 2, & ! Source in a cell
         SRC_SURFACE = 3    ! Source on a surface
  
    integer, parameter ::        &
         PROB_SOURCE      = 1, & ! External source problem
         PROB_CRITICALITY = 2    ! Criticality problem
  
    ! Interpolation flag
    integer, parameter ::     &
  
negative.code:        ONE          = 1.0_8,             &
         TWO          = 2.0_8
  
    ! ============================================================================
    ! GEOMETRY-RELATED CONSTANTS
  
    ! Boundary conditions
    integer, parameter ::    &
  