C
      integer NMXHKK
      integer nhkk,nevhkk,isthkk,idhkk,jmohkk,jdahkk
      double precision phkk,vhkk,whkk
      integer idres,idxres,nobam,idbam,idch,npoint
C
      PARAMETER (NMXHKK=49998) 
      COMMON /HKKEVT/ NHKK,NEVHKK,ISTHKK(NMXHKK),IDHKK(NMXHKK),
     &                JMOHKK(2,NMXHKK),JDAHKK(2,NMXHKK),
     &                PHKK(5,NMXHKK),VHKK(4,NMXHKK),WHKK(4,NMXHKK)
      COMMON /EXTEVT/ IDRES(NMXHKK),IDXRES(NMXHKK),NOBAM(NMXHKK),
     &                IDBAM(NMXHKK),IDCH(NMXHKK),NPOINT(10)
C
C                       WHKK(4,NMXHKK) GIVES POSITIONS AND TIMES IN
C                       PROJECTILE FRAME, THE CHAINS ARE CREATED ON
C                       THE POSITIONS OF THE PROJECTILE NUCLEONS
C                       IN THE PROJECTILE FRAME (TARGET NUCLEONS IN
C                       TARGET FRAME) BOTH POSITIONS ARE THREFORE NOT
C                       COMPLETELY CONSISTENT. THE TIMES IN THE
C                       PROJECTILE FRAME HOWEVER ARE OBTAINED BY
C                       LORENTZ TRANSFORMING FROM THE LAB SYSTEM.
C
C  Based on the proposed standard COMMON block (Sjostrand Memo 17.3,89)
C
C NMXHKK: maximum numbers of entries (partons/particles) that can be
C    stored in the commonblock.
C
C NHKK: the actual number of entries stored in current event. These are
C    found in the first NHKK positions of the respective arrays below.
C    Index IHKK, 1 <= IHKK <= NHKK, is below used to denote a given
C    entry.
C
C ISTHKK(IHKK): status code for entry IHKK, with following meanings:
C    = 0 : null entry.
C    = 1 : an existing entry, which has not decayed or fragmented.
C        This is the main class of entries which represents the
C        "final state" given by the generator.
C    = 2 : an entry which has decayed or fragmented and therefore
C        is not appearing in the final state, but is retained for
C        event history information.
C    = 3 : a documentation line, defined separately from the event
C        history. (incoming reacting
C        particles, etc.)
C    = 4 - 10 : undefined, but reserved for future standards.
C    = 11 - 20 : at the disposal of each model builder for constructs
C        specific to his program, but equivalent to a null line in the
C        context of any other program. One example is the cone defining
C        vector of HERWIG, another cluster or event axes of the JETSET
C        analysis routines.
C    = 21 - : at the disposal of users, in particular for event tracking
C        in the detector.
C
C IDHKK(IHKK) : particle identity, according to the Particle Data Group
C    standard.
C
C JMOHKK(1,IHKK) : pointer to the position where the mother is stored.
C    The value is 0 for initial entries.
C
C JMOHKK(2,IHKK) : pointer to position of second mother. Normally only
C    one mother exist, in which case the value 0 is used. In cluster
C    fragmentation models, the two mothers would correspond to the q
C    and qbar which join to form a cluster. In string fragmentation,
C    the two mothers of a particle produced in the fragmentation would
C    be the two endpoints of the string (with the range in between
C    implied).
C
C JDAHKK(1,IHKK) : pointer to the position of the first daughter. If an
C    entry has not decayed, this is 0.
C
C JDAHKK(2,IHKK) : pointer to the position of the last daughter. If an
C    entry has not decayed, this is 0. It is assumed that the daughters
C    of a particle (or cluster or string) are stored sequentially, so
C    that the whole range JDAHKK(1,IHKK) - JDAHKK(2,IHKK) contains
C    daughters. Even in cases where only one daughter is defined (e.g.
C    K0 -> K0S) both values should be defined, to make for a uniform
C    approach in terms of loop constructions.
C
C PHKK(1,IHKK) : momentum in the x direction, in GeV/c.
C
C PHKK(2,IHKK) : momentum in the y direction, in GeV/c.
C
C PHKK(3,IHKK) : momentum in the z direction, in GeV/c.
C
C PHKK(4,IHKK) : energy, in GeV.
C
C PHKK(5,IHKK) : mass, in GeV/c**2. For spacelike partons, it is allowed
C    to use a negative mass, according to PHKK(5,IHKK) = -sqrt(-m**2).
C
C VHKK(1,IHKK) : production vertex x position, in mm.
C
C VHKK(2,IHKK) : production vertex y position, in mm.
C
C VHKK(3,IHKK) : production vertex z position, in mm.
C
C VHKK(4,IHKK) : production time, in mm/c (= 3.33*10**(-12) s).
C********************************************************************