Tracking which node responds to which is getting a little twitchy, so, to be clear, this was written (before the thread got so complicated) in response to Re^6: Getting an unknown error.

----END UPDATE of 2015-04-25----

Excellent discussion, AnomalousMonk, for which, ++.

BUT, it falls short of persuading me: I hew to the notion that docs at the perldoc docname level of authority should accept a (small!) bit of verbosity to handle significant exceptions... or perhaps rephrase to avoid making (what I see as) a manifestly false statement; one which is NOT clarified nor constrained by its context.

In this case, I would argue that it is [ inaccurate | misleading | false ] to state categorically and without qualification (as does perlvar):

These variables are read-only and dynamically-scoped.

I acknowledge a possible reason for believing otherwise than I do... that the context is discussion of the $n variables as used in regexen (under the subhead, "Variables related to regular expressions)."

But, I don't think even that is adequate justification for phrasing that appears to be at the root of an widely-held but inaccurate mime.

Perhaps the doc editors [ could | should ] revise the perlvar statement by adding the word "generally" and extend it by noting that $n can -- BUT SHOULD NOT - be used as an iterator (that may not be sufficiently broad, but I hope it suggests an approach. I find NO caveat on that point in the perldoc .... collection.

Of course, maybe someone will correct me, and find a limiting counterstatement in authoritative documentation; other than the content of this thread) but