Current Position Information
Previous exit limit (target) price
At position entry time, PrevExitLimit is set to 0.
On each bar that the position is open, after the ExitLimit formula is calculated, its value is placed in PrevExitLimit.
This makes it possible to implement a "trailing target", or any type of price target concept that needs to refer to its own prior value to be calculated.
(Previously this required using the Data Section and was therefore more complex.)
It is also possible for a strategy to refer to the current exit limit price of another strategy by using Extern(@other, PrevExitLimit).