PVDs of important diagnostic lines with associated contours. The red dashed contour indicates the C iv emission and the horizontal dotted lines give the peak location of the two optical knots. The shaded area indicates the centroid of the inner X-ray jet (spatial extent: ), the blue line visualizes the velocity of the C iv emission, and the blue contours pertain to the central jet emission in the 1999 STIS data. Contours start at 7 × 10^-14 erg s^-1 cm^-2 Å^-1 (increase by ) and at 2.5 × 10^-14 erg s^-1 cm^-2 Å^-1 (increase by a factor of 2) for C iv and optical emission, respectively.