setjmp/longjmp if the states were not on the stack. (of course nobody would be so crazy to actually use longjmp, just properly save the stack state: env and control)

if jumping back into inner states (i.e. out of control stacks), the stack frame needs to be preserved also. as in call/cc later.

Sounds like an implementation for how to managing scopes using stack frames with some state machine like elements to it

> Can someone please translate into more common vernacular?

If I were to read that, it’d be common lisp. :D