Hi Frugal One,
Interesting point you drew attention to:
PC $s/N(1-0.1) where 0.1 is my SAFE of 10%.
In the Diagram you mentioned the SAFE appeared in the Formula as a Percentage
$s/N(1-S%)
Which is mathematically wrong, and you spotted it. . .and made the 10% ----> = 0.1 as a Fraction. It surprised me that Mr Torres did not correct that after it was published. Obviously most AIMers could, just as you did, come to that point on the basis of experience with AIM, but for newcomers it may have caused "going into dead-end streets on various occasions.
On the Question of the Holding Zone this:
The clue is in the answer of the Trade Price € 176.xx. If you compare that Advised Trade Price (ATP) you can calculate the Holding Zone on the basis of the previous Trade Price. . .PTP
HZ(%) = (ATP - PTP)/PTP*100% for a Sell Point. . .HZ is Positive
HZ(%) = (ATP - PTP)/PTP*100% for a Buy Point . . .HZ is Negative
So the Hold Zone is a calculated Value that arises from other choices rather than arbitrarily being set at the Starting Point. If all the choices for the other parameters are effectively logically chosen on the basis of Stock Price behavior then the Holding Zones are a more effectively determined than arbitrary values. That is how I understood this method that was explained quite some years ago.