I remember Mark's system, it was good to use cos frankly it needed no computer once you got some experience.
It was a good starting point, basic.

My "system", has not changed one bit for well over 10 years. I have not seen it posted anywhere on any racing forum yet, so I am not aware if anyone else uses it.
Does it work? Does it profit? and Does it lose?
Yes to all 3, it's HOW one plays their "system".

The point is, look for what is comfortable with you.