On surveys and site plans, I've often found treelines. These look like the below image, and serve to delineate in a very approximate way the areas full of trees and those that aren't:
Is there a standard for where the line should be drawn, in terms of either tree trunks or canopies? For example, in the image below, should line A approximately run down the canopies of the trees closest to the outside? Should line B approximately run down the trunks of those trees?
I am aware that these lines are all very approximate and one should never read too much into them. However, before approximating something, no matter how roughly, I'd like to know what the target to be aiming at is. (And likewise for interpreting someone else's approximation.)