You can use any part of this code in your own work provided that this source is acknowledged.
PROGRAM TLM3D
*************************************************************
* *
* Transmission-line modelling of electromagnetic fields in *
* 3-dimensions using the symmetrical condensed node. *
* *
* Written by: *
* J L Herring *
* *
* Address: *
* Department of Electrical & Computer Engineering *
* University of Victoria *
* Victoria, B.C., Canada. *
* *
* E-mail: jherring@ece.uvic.ca *
* WWW: http://www.wjrh.ece.uvic.ca/tlm/ *
* *
* History: *
* Date started : 10 Dec 1995 *
* Updated : 10 Dec 1995 (HP-UX) 1.00 *
* Current version : 30 Jun 1996 (HP-UX) 1.10 *
* - more efficient scattering *
* - two-sided internal boundaries *
* *
*************************************************************
IMPLICIT NONE
*---- constant declarations
CHARACTER*(*) VERSN
INTEGER INUNT,OUTUNT
INTEGER XMAX0,YMAX0,ZMAX0
INTEGER NMBCS0,NMNEX0,NMNOU0
INTEGER PYNX,PZNX,PXNY,PZNY,PYNZ,PXNZ
INTEGER PYPZ,PZPY,PZPX,PXPZ,PXPY,PYPX
REAL Z0
PARAMETER ( VERSN = '1.10' )
PARAMETER ( INUNT=7,OUTUNT=8 )
PARAMETER ( XMAX0=16,YMAX0=16,ZMAX0=16 )
PARAMETER ( NMBCS0=20,NMNEX0=10,NMNOU0=10 )
PARAMETER ( PYNX= 1,PZNX= 2,PXNY= 3,PZNY= 4,PYNZ= 5,PXNZ= 6 )
PARAMETER ( PYPZ= 7,PZPY= 8,PZPX= 9,PXPZ=10,PXPY=11,PYPX=12 )
PARAMETER ( Z0=376.7 )
*---- variable declarations
CHARACTER*80 LINE,COMM
CHARACTER*40 INNAME,OUTNAM
CHARACTER*2 LORIEN
CHARACTER TYP,DIRN,LSIGN
LOGICAL EX
INTEGER ERR,N,X,Y,Z,I
INTEGER X1,Y1,Z1,D,T
INTEGER XMAX,YMAX,ZMAX,NUMDT
INTEGER NUMBCS,NUMNEX,NUMNOU
REAL DL,VE,VH,OUT
REAL VYNX,VZNX,VXNY,VZNY,VYNZ,VXNZ
REAL VYPZ,VZPY,VZPX,VXPZ,VXPY,VYPX
REAL RHO,V0,VTEMP,VDIFF
*---- array declarations
CHARACTER BDIRN(NMBCS0),BSIGN(NMBCS0)
INTEGER BOX1(NMBCS0),BOY1(NMBCS0),BOZ1(NMBCS0)
INTEGER BOX2(NMBCS0),BOY2(NMBCS0),BOZ2(NMBCS0)
REAL BRHO(NMBCS0)
CHARACTER*3 NEID(NMNEX0)
INTEGER NEX1(NMNEX0),NEY1(NMNEX0),NEZ1(NMNEX0)
INTEGER NEX2(NMNEX0),NEY2(NMNEX0),NEZ2(NMNEX0)
REAL NEAMP(NMNEX0)
CHARACTER*2 NOID(NMNOU0)
INTEGER NOX1(NMNOU0),NOY1(NMNOU0),NOZ1(NMNOU0)
COMMON/COMV/V
REAL V(12,XMAX0,YMAX0,ZMAX0)
*---- display program details
WRITE(*,*)
WRITE(*,*) 'TLM3D (v'//VERSN//') - '//
; 'Transmission-Line Modelling in 3-Dimensions'
WRITE(*,*)
WRITE(*,*) 'Limits :'
WRITE(*,99010) 'mesh ',XMAX0,YMAX0,ZMAX0
WRITE(*,99020) 'boundaries',NMBCS0
WRITE(*,99020) 'excite ',NMNEX0
WRITE(*,99020) 'output ',NMNOU0
WRITE(*,*)
99010 FORMAT(1X,' ',A,' = ',I2,' x ',I2,' x ',I2)
99020 FORMAT(1X,' ',A,' = ',I2)
*---- open input file
WRITE(*,*) 'Name of input file : '
READ(*,'(A)') INNAME
INQUIRE(FILE=INNAME,EXIST=EX)
IF (.NOT.EX) STOP 'File does not exist'
OPEN(INUNT,FILE=INNAME,STATUS='OLD',ACCESS='SEQUENTIAL',
; FORM='FORMATTED',IOSTAT=ERR)
IF (ERR.NE.0) STOP 'File cannot be opened'
REWIND(INUNT)
*---- set default data
OUTNAM = '?'
XMAX = XMAX0
YMAX = YMAX0
ZMAX = ZMAX0
DL = 1.0
NUMDT = 0
NUMBCS = 0
NUMNEX = 0
NUMNOU = 0
*---- read input file
11010 READ(INUNT,'(A)',IOSTAT=ERR) LINE
IF (ERR.NE.0) STOP 'Error reading file'
IF (LINE(1:1).EQ.'!') GOTO 11010
IF (LINE(1:1).NE.':') STOP 'Start of data expected'
COMM = LINE(2:80)
*------ mesh size
IF (COMM.EQ.'MESH') THEN
READ(INUNT,*) XMAX,YMAX,ZMAX
IF (XMAX.GT.XMAX0.OR.YMAX.GT.YMAX0.OR.ZMAX.GT.ZMAX0)
; STOP 'Too big'
*------ node spacing
ELSE IF (COMM.EQ.'DL') THEN
READ(INUNT,*) DL
*------ number of timesteps
ELSE IF (COMM.EQ.'TIMESTEPS') THEN
READ(INUNT,*) NUMDT
*------ output file
ELSE IF (COMM.EQ.'OUTPUT_FILE') THEN
READ(INUNT,*) OUTNAM
*------ boundaries
ELSE IF (COMM.EQ.'BOUNDARIES') THEN
READ(INUNT,*) NUMBCS
IF (NUMBCS.GT.NMBCS0) STOP 'Too many boundaries'
DO 12010, I = 1, NUMBCS
READ(INUNT,*) BRHO(I),LORIEN,BOX1(I),BOY1(I),BOZ1(I),
; BOX2(I),BOY2(I),BOZ2(I)
BDIRN(I) = LORIEN(1:1)
BSIGN(I) = LORIEN(2:2)
IF ((BSIGN(I).NE.'N'.AND.BSIGN(I).NE.'P'.AND.
; BSIGN(I).NE.'0').OR.
; BOX1(I).LT.1.OR.BOX2(I).GT.XMAX.OR.BOX2(I).LT.BOX1(I).OR.
; BOY1(I).LT.1.OR.BOY2(I).GT.YMAX.OR.BOY2(I).LT.BOY1(I).OR.
; BOZ1(I).LT.1.OR.BOZ2(I).GT.ZMAX.OR.BOZ2(I).LT.BOZ1(I).OR.
; BDIRN(I).EQ.'X'.AND.(BOX1(I).NE.BOX2(I).OR.
; (BSIGN(I).EQ.'0'.AND.BOX2(I).EQ.XMAX)).OR.
; BDIRN(I).EQ.'Y'.AND.(BOY1(I).NE.BOY2(I).OR.
; (BSIGN(I).EQ.'0'.AND.BOY2(I).EQ.YMAX)).OR.
; BDIRN(I).EQ.'Z'.AND.(BOZ1(I).NE.BOZ2(I).OR.
; (BSIGN(I).EQ.'0'.AND.BOZ2(I).EQ.ZMAX)))
; STOP 'Bad boundary coordinates'
12010 CONTINUE
*------ excitation
ELSE IF (COMM.EQ.'EXCITE') THEN
READ(INUNT,*) NUMNEX
IF (NUMNEX.GT.NMNEX0) STOP 'Too many excite'
DO 13010, I = 1, NUMNEX
READ(INUNT,*) NEID(I),NEAMP(I),NEX1(I),NEY1(I),NEZ1(I),
; NEX2(I),NEY2(I),NEZ2(I)
IF (NEX1(I).LT.1.OR.NEX2(I).GT.XMAX.OR.NEX2(I).LT.NEX1(I).OR.
; NEY1(I).LT.1.OR.NEY2(I).GT.YMAX.OR.NEY2(I).LT.NEY1(I).OR.
; NEZ1(I).LT.1.OR.NEZ2(I).GT.ZMAX.OR.NEZ2(I).LT.NEZ1(I))
; STOP 'Bad excitation coordinates'
13010 CONTINUE
*------ output
ELSE IF (COMM.EQ.'OUTPUT') THEN
READ(INUNT,*) NUMNOU
IF (NUMNOU.GT.NMNOU0) STOP 'Too many output'
DO 14010, I = 1, NUMNOU
READ(INUNT,*) NOID(I),NOX1(I),NOY1(I),NOZ1(I)
IF (NOX1(I).LT.1.OR.NOX1(I).GT.XMAX.OR.
; NOY1(I).LT.1.OR.NOY1(I).GT.YMAX.OR.
; NOZ1(I).LT.1.OR.NOZ1(I).GT.ZMAX)
; STOP 'Bad output coordinates'
14010 CONTINUE
*---- end of read
ELSE IF (COMM.NE.'END') THEN
STOP 'Data not recognised'
END IF
IF (COMM.NE.'END') GOTO 11010
CLOSE(INUNT)
WRITE(*,*) 'Input file closed'
*---- open output file
IF (OUTNAM.EQ.'?') THEN
WRITE(*,*) 'Name of output file : '
READ(*,'(A)') OUTNAM
END IF
OPEN(OUTUNT,FILE=OUTNAM,STATUS='NEW',ACCESS='SEQUENTIAL',
; FORM='FORMATTED',IOSTAT=ERR)
IF (ERR.NE.0) STOP 'Output file cannot be opened'
*---- clear array
DO 21010, Z = 1, ZMAX
DO 21020, Y = 1, YMAX
DO 21030, X = 1, XMAX
DO 21040, D = 1, 12
V(D,X,Y,Z) = 0.0
21040 CONTINUE
21030 CONTINUE
21020 CONTINUE
21010 CONTINUE
*---- excite
DO 22010, N = 1, NUMNEX
TYP = NEID(N)(1:1)
DIRN = NEID(N)(2:2)
IF (TYP.EQ.'E') THEN
VE = - DL * NEAMP(N) / 2.0
ELSE IF (TYP.EQ.'H') THEN
VH = DL * Z0 * NEAMP(N) / 2.0
ELSE
STOP 'Excitation field error'
END IF
DO 22020, Z = NEZ1(N), NEZ2(N)
DO 22030, Y = NEY1(N), NEY2(N)
DO 22040, X = NEX1(N), NEX2(N)
IF (TYP.EQ.'E') THEN
IF (DIRN.EQ.'X') THEN
V(PYNX,X,Y,Z) = V(PYNX,X,Y,Z) + VE
V(PZNX,X,Y,Z) = V(PZNX,X,Y,Z) + VE
V(PYPX,X,Y,Z) = V(PYPX,X,Y,Z) + VE
V(PZPX,X,Y,Z) = V(PZPX,X,Y,Z) + VE
ELSE IF (DIRN.EQ.'Y') THEN
V(PZNY,X,Y,Z) = V(PZNY,X,Y,Z) + VE
V(PXNY,X,Y,Z) = V(PXNY,X,Y,Z) + VE
V(PZPY,X,Y,Z) = V(PZPY,X,Y,Z) + VE
V(PXPY,X,Y,Z) = V(PXPY,X,Y,Z) + VE
ELSE IF (DIRN.EQ.'Z') THEN
V(PXNZ,X,Y,Z) = V(PXNZ,X,Y,Z) + VE
V(PYNZ,X,Y,Z) = V(PYNZ,X,Y,Z) + VE
V(PXPZ,X,Y,Z) = V(PXPZ,X,Y,Z) + VE
V(PYPZ,X,Y,Z) = V(PYPZ,X,Y,Z) + VE
ELSE
STOP 'E-field excitation error'
END IF
ELSE IF (TYP.EQ.'H') THEN
IF (DIRN.EQ.'X') THEN
V(PZNY,X,Y,Z) = V(PZNY,X,Y,Z) + VH
V(PYNZ,X,Y,Z) = V(PYNZ,X,Y,Z) - VH
V(PZPY,X,Y,Z) = V(PZPY,X,Y,Z) - VH
V(PYPZ,X,Y,Z) = V(PYPZ,X,Y,Z) + VH
ELSE IF (DIRN.EQ.'Y') THEN
V(PXNZ,X,Y,Z) = V(PXNZ,X,Y,Z) + VH
V(PZNX,X,Y,Z) = V(PZNX,X,Y,Z) - VH
V(PXPZ,X,Y,Z) = V(PXPZ,X,Y,Z) - VH
V(PZPX,X,Y,Z) = V(PZPX,X,Y,Z) + VH
ELSE IF (DIRN.EQ.'Z') THEN
V(PYNX,X,Y,Z) = V(PYNX,X,Y,Z) + VH
V(PXNY,X,Y,Z) = V(PXNY,X,Y,Z) - VH
V(PYPX,X,Y,Z) = V(PYPX,X,Y,Z) - VH
V(PXPY,X,Y,Z) = V(PXPY,X,Y,Z) + VH
ELSE
STOP 'H-field excitation error'
END IF
END IF
22040 CONTINUE
22030 CONTINUE
22020 CONTINUE
22010 CONTINUE
*---- start calculation
WRITE(*,*) 'Start of calculation'
DO 30010, T = 1, NUMDT
WRITE(*,99100) 100.0*REAL(T-1)/REAL(NUMDT)
99100 FORMAT(1X,F6.3,' %')
*---- output
DO 41010, N = 1, NUMNOU
TYP = NOID(N)(1:1)
DIRN = NOID(N)(2:2)
Z = NOZ1(N)
Y = NOY1(N)
X = NOX1(N)
IF (TYP.EQ.'E') THEN
IF (DIRN.EQ.'X') THEN
OUT = V(PYNX,X,Y,Z) + V(PZNX,X,Y,Z) +
; V(PYPX,X,Y,Z) + V(PZPX,X,Y,Z)
ELSE IF (DIRN.EQ.'Y') THEN
OUT = V(PZNY,X,Y,Z) + V(PXNY,X,Y,Z) +
; V(PZPY,X,Y,Z) + V(PXPY,X,Y,Z)
ELSE IF (DIRN.EQ.'Z') THEN
OUT = V(PXNZ,X,Y,Z) + V(PYNZ,X,Y,Z) +
; V(PXPZ,X,Y,Z) + V(PYPZ,X,Y,Z)
ELSE
STOP 'E-field output error'
END IF
OUT = - OUT / DL / 2.0
ELSE IF (TYP.EQ.'H') THEN
IF (DIRN.EQ.'X') THEN
OUT = V(PZNY,X,Y,Z) - V(PYNZ,X,Y,Z) -
; V(PZPY,X,Y,Z) + V(PYPZ,X,Y,Z)
ELSE IF (DIRN.EQ.'Y') THEN
OUT = V(PXNZ,X,Y,Z) - V(PZNX,X,Y,Z) -
; V(PXPZ,X,Y,Z) + V(PZPX,X,Y,Z)
ELSE IF (DIRN.EQ.'Z') THEN
OUT = V(PYNX,X,Y,Z) - V(PXNY,X,Y,Z) -
; V(PYPX,X,Y,Z) + V(PXPY,X,Y,Z)
ELSE
STOP 'H-field output error'
END IF
OUT = OUT / Z0 / DL / 2.0
ELSE
STOP 'Output field error'
END IF
WRITE(OUTUNT,99200) OUT
99200 FORMAT(1X,E13.6)
41010 CONTINUE
*---- scatter
DO 42010, Z = 1, ZMAX
DO 42020, Y = 1, YMAX
DO 42030, X = 1, XMAX
VYNX = V(PYNX,X,Y,Z)
VZNX = V(PZNX,X,Y,Z)
VXNY = V(PXNY,X,Y,Z)
VZNY = V(PZNY,X,Y,Z)
VYNZ = V(PYNZ,X,Y,Z)
VXNZ = V(PXNZ,X,Y,Z)
VYPZ = V(PYPZ,X,Y,Z)
VZPY = V(PZPY,X,Y,Z)
VZPX = V(PZPX,X,Y,Z)
VXPZ = V(PXPZ,X,Y,Z)
VXPY = V(PXPY,X,Y,Z)
VYPX = V(PYPX,X,Y,Z)
VDIFF = VXPY - VXNY
VTEMP = 0.5 * ( VZNX + VZPX + VDIFF )
V(PYPX,X,Y,Z) = VTEMP
V(PYNX,X,Y,Z) = VTEMP - VDIFF
VDIFF = VXPZ - VXNZ
VTEMP = 0.5 * ( VYNX + VYPX + VDIFF )
V(PZPX,X,Y,Z) = VTEMP
V(PZNX,X,Y,Z) = VTEMP - VDIFF
VDIFF = VYPZ - VYNZ
VTEMP = 0.5 * ( VXNY + VXPY + VDIFF )
V(PZPY,X,Y,Z) = VTEMP
V(PZNY,X,Y,Z) = VTEMP - VDIFF
VDIFF = VYPX - VYNX
VTEMP = 0.5 * ( VZNY + VZPY + VDIFF )
V(PXPY,X,Y,Z) = VTEMP
V(PXNY,X,Y,Z) = VTEMP - VDIFF
VDIFF = VZPX - VZNX
VTEMP = 0.5 * ( VYNZ + VYPZ + VDIFF )
V(PXPZ,X,Y,Z) = VTEMP
V(PXNZ,X,Y,Z) = VTEMP - VDIFF
VDIFF = VZPY - VZNY
VTEMP = 0.5 * ( VXNZ + VXPZ + VDIFF )
V(PYPZ,X,Y,Z) = VTEMP
V(PYNZ,X,Y,Z) = VTEMP - VDIFF
42030 CONTINUE
42020 CONTINUE
42010 CONTINUE
*---- boundaries
DO 43010, N = 1, NUMBCS
DIRN = BDIRN(N)
LSIGN = BSIGN(N)
RHO = BRHO(N)
IF (DIRN.EQ.'X') THEN
X = BOX1(N)
IF (LSIGN.EQ.'N'.AND.X.EQ.1) THEN
DO 43110, Z = BOZ1(N), BOZ2(N)
DO 43120, Y = BOY1(N), BOY2(N)
V(PXNY,X,Y,Z) = RHO * V(PXNY,X,Y,Z)
V(PXNZ,X,Y,Z) = RHO * V(PXNZ,X,Y,Z)
43120 CONTINUE
43110 CONTINUE
ELSE IF (LSIGN.EQ.'P'.AND.X.EQ.XMAX) THEN
DO 43130, Z = BOZ1(N), BOZ2(N)
DO 43140, Y = BOY1(N), BOY2(N)
V(PXPZ,X,Y,Z) = RHO * V(PXPZ,X,Y,Z)
V(PXPY,X,Y,Z) = RHO * V(PXPY,X,Y,Z)
43140 CONTINUE
43130 CONTINUE
ELSE
IF (LSIGN.EQ.'N') X = X - 1
X1 = X + 1
DO 43150, Z = BOZ1(N), BOZ2(N)
DO 43160, Y = BOY1(N), BOY2(N)
VTEMP = V(PXPY,X,Y,Z)
V(PXPY,X,Y,Z) = RHO * V(PXNY,X1,Y,Z)
V(PXNY,X1,Y,Z) = RHO * VTEMP
VTEMP = V(PXPZ,X,Y,Z)
V(PXPZ,X,Y,Z) = RHO * V(PXNZ,X1,Y,Z)
V(PXNZ,X1,Y,Z) = RHO * VTEMP
43160 CONTINUE
43150 CONTINUE
END IF
ELSE IF (DIRN.EQ.'Y') THEN
Y = BOY1(N)
IF (LSIGN.EQ.'N'.AND.Y.EQ.1) THEN
DO 43210, Z = BOZ1(N), BOZ2(N)
DO 43220, X = BOX1(N), BOX2(N)
V(PYNZ,X,Y,Z) = RHO * V(PYNZ,X,Y,Z)
V(PYNX,X,Y,Z) = RHO * V(PYNX,X,Y,Z)
43220 CONTINUE
43210 CONTINUE
ELSE IF (LSIGN.EQ.'P'.AND.Y.EQ.YMAX) THEN
DO 43230, Z = BOZ1(N), BOZ2(N)
DO 43240, X = BOX1(N), BOX2(N)
V(PYPZ,X,Y,Z) = RHO * V(PYPZ,X,Y,Z)
V(PYPX,X,Y,Z) = RHO * V(PYPX,X,Y,Z)
43240 CONTINUE
43230 CONTINUE
ELSE
IF (LSIGN.EQ.'N') Y = Y - 1
Y1 = Y + 1
DO 43250, Z = BOZ1(N), BOZ2(N)
DO 43260, X = BOX1(N), BOX2(N)
VTEMP = V(PYPZ,X,Y,Z)
V(PYPZ,X,Y,Z) = RHO * V(PYNZ,X,Y1,Z)
V(PYNZ,X,Y1,Z) = RHO * VTEMP
VTEMP = V(PYPX,X,Y,Z)
V(PYPX,X,Y,Z) = RHO * V(PYNX,X,Y1,Z)
V(PYNX,X,Y1,Z) = RHO * VTEMP
43260 CONTINUE
43250 CONTINUE
END IF
ELSE IF (DIRN.EQ.'Z') THEN
Z = BOZ1(N)
IF (LSIGN.EQ.'N'.AND.Z.EQ.1) THEN
DO 43310, Y = BOY1(N), BOY2(N)
DO 43320, X = BOX1(N), BOX2(N)
V(PZNX,X,Y,Z) = RHO * V(PZNX,X,Y,Z)
V(PZNY,X,Y,Z) = RHO * V(PZNY,X,Y,Z)
43320 CONTINUE
43310 CONTINUE
ELSE IF (LSIGN.EQ.'P'.AND.Z.EQ.ZMAX) THEN
DO 43330, Y = BOY1(N), BOY2(N)
DO 43340, X = BOX1(N), BOX2(N)
V(PZPX,X,Y,Z) = RHO * V(PZPX,X,Y,Z)
V(PZPY,X,Y,Z) = RHO * V(PZPY,X,Y,Z)
43340 CONTINUE
43330 CONTINUE
ELSE
IF (LSIGN.EQ.'N') Z = Z - 1
Z1 = Z + 1
DO 43350, Y = BOY1(N), BOY2(N)
DO 43360, X = BOX1(N), BOX2(N)
VTEMP = V(PZPX,X,Y,Z)
V(PZPX,X,Y,Z) = RHO * V(PZNX,X,Y,Z1)
V(PZNX,X,Y,Z1) = RHO * VTEMP
VTEMP = V(PZPY,X,Y,Z)
V(PZPY,X,Y,Z) = RHO * V(PZNY,X,Y,Z1)
V(PZNY,X,Y,Z1) = RHO * VTEMP
43360 CONTINUE
43350 CONTINUE
END IF
ELSE
STOP 'Boundary direction error'
END IF
43010 CONTINUE
*---- connect
DO 44010, Z = 1, ZMAX
Z1 = Z + 1
DO 44020, Y = 1, YMAX
Y1 = Y + 1
DO 44030, X = 1, XMAX
X1 = X + 1
IF (X.LT.XMAX) THEN
V0 = V(PXPZ,X,Y,Z)
V(PXPZ,X,Y,Z) = V(PXNZ,X1,Y,Z)
V(PXNZ,X1,Y,Z) = V0
V0 = V(PXPY,X,Y,Z)
V(PXPY,X,Y,Z) = V(PXNY,X1,Y,Z)
V(PXNY,X1,Y,Z) = V0
END IF
IF (Y.LT.YMAX) THEN
V0 = V(PYPZ,X,Y,Z)
V(PYPZ,X,Y,Z) = V(PYNZ,X,Y1,Z)
V(PYNZ,X,Y1,Z) = V0
V0 = V(PYPX,X,Y,Z)
V(PYPX,X,Y,Z) = V(PYNX,X,Y1,Z)
V(PYNX,X,Y1,Z) = V0
END IF
IF (Z.LT.ZMAX) THEN
V0 = V(PZPY,X,Y,Z)
V(PZPY,X,Y,Z) = V(PZNY,X,Y,Z1)
V(PZNY,X,Y,Z1) = V0
V0 = V(PZPX,X,Y,Z)
V(PZPX,X,Y,Z) = V(PZNX,X,Y,Z1)
V(PZNX,X,Y,Z1) = V0
END IF
44030 CONTINUE
44020 CONTINUE
44010 CONTINUE
*---- end calculation
30010 CONTINUE
*---- close output file
CLOSE(OUTUNT)
WRITE(*,*) 'Output file closed'
WRITE(*,*)
END
J. L. Herring, 30 June 1996.