P.T. I was responding to this part of your message (post #102)
"sell your position if price climbs 10 to 20 percent above the 20-day ma line (depending on the volatility of the trade vehicle),"
I only wanted to point out the bands can give a trader a visual method to see when a stock has moved 10% or 20% from the mean in this case the 20 MA. Depending on volatility any MA can be used as the mean for the envelope.