Meaning of "Sentry" in Zenith Sentry 2?; teletext

[Jeffhs]

I've been wondering for some time what the meaning of the term "Sentry 2", as applied to certain models of Zenith color televisions of 1990s vintage, actually was. I have one of those sets (19" table model), but see no reference in the instruction manual to any kind of automatic color correction schemes, so I honestly don't think this set has anything like the old (ca. 1970s) Color Sentry system. My set only has two options in the video OSD menu for color control, Preset and Custom.

BTW, my Zenith Sentry 2 set also has a menu option for teletext. I have owned this set close to eleven years, and the only thing I have ever seen when I switch the teletext decoder on (I used the TV mostly on cable the four years it was my main set) is a black box covering much of the lower half of the picture. Was teletext ever used on a regular basis by US or Canadian television stations and/or cable systems? I remember reading somewhere that Atlanta's WTBS (the local TV station, not TBS Superstation) was running a teletext test some time in the '90s, but I could never find any information on it as to what was contained in the test broadcast (if any) or anything else pertaining to such a test. If there was nothing to be seen on teletext anywhere in this country or in Canada, I honestly have to wonder why Zenith put a teletext decoder in the TV in the first place. Later models of Zenith TVs, say from the late '90s to now, do not have teletext decoders to the best of my knowledge; I don't think the new Zenith-branded LG sets have this useless feature either. Perhaps by then Zenith saw the light and realized the teletext decoder was a frill just about everyone could do without.