C++
C*********  INCLUDE FILE,  'MC_GEOM.INC'  **********
C
C  08 Feb 1994: converted from COMMON to STRUCTUREs.  Added WT, M, and POL to
C               particle record.  Require Y direction to be vertical (for 
C               gravity). [PAS]
C  17 Feb 1994: added BETA to surface record; type 5 boundary; made MAXP 
C               a parameter [PAS]
C  15 Feb 1995: include structure /MC_ELEMENT/ formerly in MC_ELMNT.INC [PAS]
C  04 Dec 1995: larger MAXR, MAXP; replace POL with Q and (PX,PY,PZ) [PAS]
C  27 Nov 1997: larger MAXS, MAXR, MAXP (total size 65530 bytes) [LLD,PAS]
C  14 Sep 1998: SURFACE and PARAM changed from REAL*4 to REAL*8 [PAS]
C  26 Mar 1999: larger MAXS, MAXR, MAXP (total size 121648 bytes) [Fitz,PAS]
C  30 Sep 2003: larger MAXS, MAXR, MAXP (total size 227722 bytes) [PAS]
C  14 Jun 2005: larger MAXS (total size 314432 bytes) [PAS]
C  07 Jul 2006: make MAXM (number of magnetic regions) a parameter [PAS]
C  14 Nov 2009: make usage F90 standard: "STRUCTURE" --> "TYPE" [PAS]
C
C  To change dimensions of all arrays, change maximum numbers of
C    surfaces (MAXS), regions (MAXR), element parameters (MAXP), and/or 
C    magnetic regions (MAXM) in following PARAMETER statement.
      INTEGER*4 MAXS, MAXR, MAXP, MAXM
      PARAMETER (MAXS=400, MAXR=255, MAXP=8000, MAXM=50)
C
C  Definitions of surface parameters and array of boundaries of surfaces:
C    SURFACE is a derived type containing 10 coefficients of a general
C      quadratic surface, of the form
C      A*(X**2) + B*X + C*(Y**2) + D*Y + E*(Z**2) + F*Z + G +
C          P*(X*Y) + Q*(Y*Z) + R*(Z*X)  =  0
C      BETA = surface roughness parameter between 0 (smooth) and 1 (cosine);
C             negative or >1 is completely random
      TYPE SURFACE
         SEQUENCE
         REAL*8 A, B, C, D, E, F, G, P, Q, R, BETA
      END TYPE
C
C    REGION is derived type containing NSURF values of the I*2 variable IGEOM, 
C      defining a region by its bounding surfaces:
C      +  if interior of region is on + side of surface
C      -  if interior of region is on - side of surface
C      0  if surface is not a boundary of the region
C      1  for ordinary surface described by roughness BETA and possibility 
C          of refraction or critical reflection 
C      2  for totally reflecting surface
C      3  for diffuse scattering surface 
C      4  for absorbing surface
C      5  special action required in previous region before crossing surface
C      6  split particle by 2 after crossing surface, treated as type 1
C     10  for boundary of a magnetic field region
C    +10  for a surface which bounds an embedded region within the region; not
C          tested to determine if within region, but tested for exit from region
C    +20  for embedded surface with possible regions on BOTH sides
      TYPE REGION
         SEQUENCE
         INTEGER*2 IGEOM(MAXS)
      END TYPE
C
C    MC_GEOM is a derived type giving the complete geometry of an instrument    
C    NSURF = number of surfaces defined
C    NREG  = number of regions defined
      TYPE MC_GEOM
         SEQUENCE
         INTEGER*4 NSURF, NREG
         TYPE(SURFACE) SURFACE(MAXS)
         TYPE(REGION)  REGION(MAXR)
      END TYPE
C 
C    MC_ELEMENT is a derived type with the variables for what happens
C    to neutrons in a REGION. Each INDEX points to the beginning of a 
C    structure within the contiguous block PARAM. The first entry in 
C    PARAM for each element identifies the type, followed by a varying
C    number of variables. Element types and parameters are defined in
C    a separate file, MC_ELMNT.INC
C    NAME      = descriptive name of a region or element
C    NEXTINDX  = pointer to next available location in PARAM
C    INDEX     = pointer into parameter block; 
C                 0 if region is NOT an "element"
C    PARAM = combined block of parameters for the whole instrument
      TYPE MC_ELEMENT
	 SEQUENCE
         CHARACTER*40 NAME(MAXR)
         INTEGER*4    NEXTINDX, INDEX(MAXR)
         REAL*8       PARAM(MAXP)
      END TYPE
C
C    PARTICLE is a derived type giving position, velocity, and polarization
C    of a neutron or other particle.
C    (X,Y,Z) = position of particle (m); define -Y = direction of gravity, 
C         +Z = nominal beam direction, +X = right; note left-handed system
C    (VX,VY,VZ) = velocity of particle (m/us)
C    TOF = time of flight of particle (us)
C    M   = atomic number of particle (e.g., 1 for neutron, 0 for photon)
C    Q   = charge number of particle (e.g., 0 for neutron, +1 for proton)
C    WT  = statistical weight of particle
C    (PX,PY,PZ) = average polarization vector, from -1.0 to +1.0
      TYPE PARTICLE
         SEQUENCE
         REAL*4 X, Y, Z, VX, VY, VZ, TOF
         REAL*4 M, Q, WT, PX, PY, PZ
      END TYPE