It's "forest corner". But I don't think anybody really knows what that means.
Graham said "veg edge" -- which is a good rhyming way for me to remember from now on. But, you're right, I'm not sure how to interpret "forest corner". He also said he and Craig (vetter) had disagreed about the best description to use. :-)
There's another symbol for "vegetation boundary", the meaning of which is also unclear, though at least the map symbol is pretty consistently a row of black dots.