Those who are interested in this indicator should go to the original authors Helweg and Stendahl, in their book:
Dynamic Trading Indicators - Winning with Value Charts and Price Action Profile by
Stendahl, David & Helweg, Mark
and the many existing threads and code samples on the TS forum. Helweg was generously enough to post it as open code in 2001 and the copyright should be acknowledged.
If you noticed in their book and code, there are two ways to trade this, one is the 21 period High or Low and the other is an absolute +8 or -8 play.
Recently, TTM revived this fairly old indicator by incorporating it with Clayburg's DDF (Day Directional Filter) and then calling it the
TTM ddf vc indicator, which tries to find the Day's trend by usually the trend of the first hour and then trade the
VC (Value Chart) in the direction of the DDF trend. The attached picture shows such a chart with all open source code.