I had found both of those with a web search and they are helpful, as far as graphic symbols.
What I was really wondering about isn't so much a legend as a list of abbreviations.
Like I say, spg is pretty obvious; well it is to me in the Ozarks because we have so many springs and the continual spg POIs happen right where the springs are, so voila
But there are other abbreviations, such as gs, that I can't seem to figure out what they are. There isn't a lot of them, but they piqued my natural curiosity.
I guess I'll have to treat them like Waymarks and go see what they are!