... is it required? I believe yes. Also, in forested areas, do we still use 0.07 mm or do we go to 0.14 mm for the border?
I believe I've seen a map that didn't use it, and I didn't like it.
It is usually a good idea. I'm sure you can come up with a situation where the map at some location is more legible without. Try not to have the bounding line too close and parallel to another black line... (e.g. at the TT, the canopy boundary was v close to another step line and it appeared like it oculd be a thick (uncrossable) line in an early draft).
Thanks! remaining unanswered: Should the canopy border go to 0.14 mm in a forested area? One of Sprint the Golden Gate venues has somewhat distinct urban and forest components, and we use 0.07 mm Step or edge in urban and 0.14 mm in forested areas per ISSOM.
Canopy border is a fixed symbol in OCAD, separate from the step/paved area. ISSOM shows it is always the same thickness. Only time I wouldn't use it is to emphasise small passageways through buildings, making it clear that there's a valid route.