262144 R Include reference counts of dumped variables (eg when using -Ds)
524288 J Do not s,t,P-debug (Jump over) opcodes within package DB
1048576 v Verbose: use in conjunction with other flags
+ 2097152 C Copy On Write
All these flags require B<-DDEBUGGING> when you compile the Perl
executable (but see L<Devel::Peek>, L<re> which may change this).
=item PERLIO
A space (or colon) separated list of PerlIO layers. If perl is built
-to use PerlIO system for IO (the default) these layers affect perl's IO.
+to use PerlIO system for IO (the default) these layers effect perl's IO.
It is conventional to start layer names with a colon e.g. C<:perlio> to
emphasise their similarity to variable "attributes". But the code that parses