C
C     INCLUDE 'initc.inc'
C     ------------------------------------------------------------------
      INTEGER MSRFCA
      PARAMETER (MSRFCA=128)
      INTEGER ISB1I,ICB1I
      REAL YLI(6),YI(29),FSRFCA(MSRFCA)
      COMMON/INITC/ISB1I,ICB1I,YLI,YI,FSRFCA
      SAVE /INITC/
C     ------------------------------------------------------------------
C     ISB1I,ICB1I... Indices of a simple and a complex blocks in which
C             the initial point of the ray is situated (see C.R.T.6.1).
C     YLI...  Array containing the values of the quantities YL(1)-YL(6)
C             (see C.R.T.5.5.4) describing the local properties of the
C             model at the initial point of the ray, see C.R.T.6.1.
C             They must not be changed outside the subroutine INIT2.
C             Description of YL
C                                                      
C     YI...   Array containing the following quantities describing the
C             properties of the rays and of the travel-time field, see
C             C.R.T.6.1:
C     YI(1)...Initial travel time.
C     YI(2)...Initial imaginary part of the complex travel time.
C     YI(3)-YI(5)... Coordinates of the initial point of the ray.
C     YI(6)-YI(8)... Covariant components of the initial slowness
C             vector.
C     YI(9)-YI(11)... Covariant components of the first basis vector of
C             the ray-centred coordinate system at the initial point of
C             the ray (perpendicular to the slowness vector
C             YI(6)-YI(8)).
C     YI(12),YI(16)     QR11,QR12
C     YI(13),YI(17)     QR21,QR22
C     YI(14),YI(18)     PR11,PR12
C     YI(15),YI(19)...  PR21,PR22
C             Elements of the ray geometrical spreading matrix QR, and
C             of the matrix PR (see C.R.T.,eq.(5.13)) at the initial
C             point of the ray.
C     YI(20),YI(21)... Take-off parameters of the ray.
C
C     The above quantities are defined in subroutine INIT2 of file
C     'init.for'.
C     INIT2
C     Following quantities Y(22)-Y(29) are defined in subroutine RPAR4
C     of file 'rpar.for'.
C     RPAR4
C
C     In addition to the above quantities describing the properties
C     defined for a single ray, there are also quantities describing
C     the properties of the discrete system of computed rays in the
C     vicinity of the computed ray.  These quantities  are
C     YI(22)..Area of the element of the ray-parameter surface,
C             corresponding to the ray, see C.R.T.,eq.(6.1).
C     YI(23),YI(24),YI(25)... Components 11, 12, 22 of the symmetric
C             matrix inverse to the specific moment of the element of
C             the ray-parameter surface corresponding to the ray, see
C             C.R.T.,eq.(6.2).
C
C     Additional quantities related to the shooting algorithm:
C     YI(26),YI(27)... Normalized take-off parameters of the ray, both
C             taking the values between 0 and 1.
C     YI(28),YI(29)... For a successful ray, values of the X1 and X2
C             functions parametrizing the reference surface.
C             X1 and X2 functions
C             Otherwise zeros.
C
C     The index of the last allocated numeric unit of array FSRFCA is
C     named MSRFCA.  Dimension MSRFCA may be adjusted if necessary.
C
C     Common block /INITC/ is included in external procedures INIT1 and
C     INIT2 of 'init.for', in OUTP of 'raycb.for', in 'rpar.for',
C     in 'writ.for', in 'scro.for',  and may be included in any other
C     subroutine.
C
C Date: 2003, April 3
C Coded by Ludek Klimes
C
C=======================================================================
C