When I said "the only thing keeping this issue open" is the message, I should acknowledge that you mentioned clarifying the documentation, but as I pointed out the documentation is already clear: it says nonlocal does not access variables in the global scope, and in your example 'a' is a variable in the global scope, because it is declared to be one.  We generally don't update PEPs after they are accepted and implemented; after that point the documentation is the real reference since the implementation may actually be different in detail than the PEP due to later enhancements. The PEP is still useful as an historical document.  (There are exceptions to that, but that is the general rule.)