-/*
- * Rewind rules. This indicates whether to stop rewinding
- * (REWIND_HALT) without touching our current scope, stop rewinding and
- * close our current scope (REWIND_REWIND), or continue (REWIND_NOHALT).
- * The scope-closing and so on occurs in the various rew_* routines.
+/*
+ * Rewinding to tok, how do we have to handle *p?
+ * REWIND_NONE: *p would delimit tok, but no tok scope is open
+ * inside *p, so there is no need to rewind anything at all.
+ * REWIND_THIS: *p matches tok, so rewind *p and nothing else.
+ * REWIND_MORE: *p is implicit, rewind it and keep searching for tok.
+ * REWIND_FORCE: *p is explicit, but tok is full, force rewinding *p.
+ * REWIND_LATER: *p is explicit and still open, postpone rewinding.
+ * REWIND_ERROR: No tok block is open at all.