Interesting chart observation

It seems that the more I stare at the VFR charts the more unique things I see, learn or relearn. The latest one was an elevation that was printed with a white background and large font as seen in the picture to the right, the 4400. Normally elevations are printed in black but with a transparent background like the 4230 below and to the right of the 4400. This can be seen on the San Francisco terminal chart roughly about 9 NM east of RHV. There is only one elevation on the entire chart printed this way. I have not found on the chart legend where this is explained but this elevation # in white represents the highest elevation on the chart page. Does anyone know where this is noted?