SUBROUTINE  PLTAX (X,Y,HE,NC,SZ,TH,V0,DV,L)

C     (X,Y)   POINT FROM WHICH AXIS ORIGINATES
C     HE      HEADING TO BE PLACED UNDER GRAPH
C     NC      NUMBER OF CHARACTERS IN HEADING
C     SZ      LENGTH OF AXIS, IN INCHES
C     TH      COUNTERCLOCKWISE ANGLE OF INCLINATION, DEGREES
C     V0      STARTING VALUE OF VARIABLE ALONG AXIS
C     DV      INCREMENT OF VARIABLE, PER INCH
C     L       =1, LETTERING ABOVE; =-1, LETTERING BELOW
C     [18-NOV-74]

      DIMENSION   HE(1)

      S=FLOAT(L)
      N=IFIX(SZ+0.5)
      CTH=COSD(TH)
      STH=SIND(TH)
      XB=X
      YB=Y
      XA=X-0.1*S*STH
      YA=Y+0.1*S*CTH
      CALL PLOT (YA,-XA,3)
      DO 20 I=1,N
      CALL PLOT (YB,-XB,2)
      XC=XB+CTH
      YC=YB+STH
      CALL PLOT (YC,-XC,2)
      XA=XA+CTH
      YA=YA+STH
      CALL PLOT (YA,-XA,2)
      XB=XC
   20 YB=YC
      IX=0
      NT=IFIX(ALOG10(DV)+0.001)
      IF (NT.LT.-1.OR.NT.GT.1) IX=NT
      ADV=DV*10.0**(-IX)
      ABV=V0*10.0**(-IX)+FLOAT(N)*ADV
      XA=XB-(0.20*S-0.05)*STH-0.0857*CTH
      YA=YB+(0.20*S-0.05)*CTH-0.0857*STH
      N=N+1
      DO 30 I=1,N
      CALL NUMBER (YA,-XA,0.1,ABV,TH-90.0,2)
      ABV=ABV-ADV
      XA=XA-CTH
   30 YA=YA-STH
      TA=FLOAT(NC+7)
      XA=X+(SZ/2.0-0.06*TA)*CTH-(-0.07+S*0.36)*STH
      YA=Y+(SZ/2.0-0.06*TA)*STH+(-0.07+S*0.36)*CTH
      IF (NC.NE.0) CALL SYMBOL (YA,-XA,0.12,HE,TH-90.0,NC)
      IF (IX.EQ.0) RETURN
      XA=XA+((TA-6.0)*0.12)*CTH
      YA=YA+((TA-6.0)*0.12)*STH
      CALL SYMBOL (YA,-XA,0.12,'(X10  )',TH-90.0,7)
      XA=XA+0.48*CTH-0.07*STH
      YA=YA+0.48*STH+0.07*CTH
      CALL NUMBER (YA,-XA,0.1,FLOAT(IX),TH-90.0,-1)
      RETURN

      END