What does enters and issues mean on old ordnance survey maps?

Oh, dude, enters and issues on old ordnance survey maps? It's like when you're navigating a treasure map and you come across a "here be dragons" warning. Enters are where you can enter a location, and issues are the problems you might encounter there, like a grumpy troll guarding a bridge. So, basically, it's just fancy old-timey talk for entrances and obstacles.