So only built-in attributes are recognized globally?

Correct. And that is how it should be. You don't want global attributes any more than you want global subroutines. I'm not saying that I like the current implementation, but at least its good that the attributes are somewhat scoped.

Since the handlers (MODIFY_CODE_ATTRIBUTES etc) are inherited one can add them to UNIVERSAL and achieve global attributes. Attribute::Handlers for instance uses this trick. This however makes it very dangerous to use attributes in modules, since attributes defined in different modules may clash. See also my previous meditation on the problems with attributes (it also links to other nodes about attributes).

lodin