from the ionizing source, or if some significant component of the high-velocity gas is optically thin (e.g., Shields, Ferland, & Peterson 1995); on physical grounds, we prefer the latter explanation. Third, the rms spectrum also shows that the optical emission varied little, if at all, during this period. The optical spectra of AGNs have broad blended features that extend from just longward of  to just shortward of , and over the range $\sim5100$–5600Å. In the mean spectrum, these  emission features are quite strong, which makes it hard to isolate the 686 emission. The blends are, however, virtually absent in the rms spectrum. Fourth, 686 is very prominent in the rms spectrum and is much broader than . The rest-frame width of this line in the rms spectrum is $\sim5430$, very typical of the line widths seen in normal Seyfert 1 galaxies. The centroid of the 686 is strongly [*blueshifted*]{} relative to , by about 1400. In order to demonstrate that these properties of the 686 profile are real, we also computed the mean and rms spectra based on (a) set A spectra obtained at the same time and (b) set B spectra obtained during the 1997 monitoring season (Year 2). 