In sci.electronics.design Ancient_Hacker wrote:
Way back in the 1950's, Waterman came out with a scope, mil version was
the AN/USM-24C. A mediocre scope- AC coupled only, 5MHz bandwidth,
poor triggering, but it did have one really neat feature-- selectable
100/10/1/.5/.2 microsecond intensity markers. They made risetime
measurements incredibly easy-- much easier than the usual routine with
lining up the xy graticule lines. Plus they looked really keen-o.

You mean that it brightens the trace if it hits that risetime, or you
get a dot on the x axis?