SUBROUTINE  PLTMT (X1,Y1,P1,X2,Y2,P2,Q)

C     [MARGIN TRIMMER]
C     THE POINTS Z1=(X1,Y1) AND Z2=(X2,Y2) ARE ADJUSTED TO ENCOMPASS
C     ONLY THAT PART OF THE LINE JOINING THEM WHICH LIES WITHIN A
C     PLOTTER PAGE WHOSE HALFWIDTHS ARE HX AND HY.
C     P1=.TRUE.  Z1 WAS MOVED
C     P2=.TRUE.  Z2 WAS MOVED
C     Q=.TRUE.   SOME PORTION OF THE LINE IS VISIBLE
C     [02-NOV-73]

      LOGICAL*1     P1,P2,Q
      DATA        HX,HY/4.50,3.25/

      EX(Y)=X1+(Y-Y1)*((X2-X1)/(Y2-Y1))
      WY(X)=Y1+(X-X1)*((Y2-Y1)/(X2-X1))

      P1=.FALSE.
      IF (ABS(X1).LE.HX) GO TO 5
      IF (X1.EQ.X2) GO TO 20
      X0=SIGN(HX,X1)
      Y1=WY(X0)
      X1=X0
      P1=.TRUE.
    5 IF (ABS(Y1).LE.HY) GO TO 10
      IF (Y1.EQ.Y2) GO TO 20
      Y0=SIGN(HY,Y1)
      X1=EX(Y0)
      Y1=Y0
      P1=.TRUE.
   10 P2=.FALSE.
      IF (ABS(X2).LE.HX) GO TO 15
      IF (X1.EQ.X2) GO TO 20
      X0=SIGN(HX,X2)
      Y2=WY(X0)
      X2=X0
      P2=.TRUE.
   15 IF (ABS(Y2).LE.HY) GO TO 20
      IF (Y1.EQ.Y2) GO TO 20
      Y0=SIGN(HY,Y2)
      X2=EX(Y0)
      Y2=Y0
      P2=.TRUE.
   20 X0=0.5*(X1+X2)
      Y0=0.5*(Y1+Y2)
      Q=(ABS(X0).LT.HX).AND.(ABS(Y0).LT.HY)
      RETURN

      END