in reply to offset of named capture buffer
See Tie::Hash::NamedCapture, http://perl5.git.perl.org/perl.git/blob/HEAD:/ext/Tie-Hash-NamedCapture/NamedCapture.xs, perlreapi, something about named_buff, http://perl5.git.perl.org/perl.git/blob?f=regcomp.c#l6468
It is possible, but not exactly easy
In Section
Seekers of Perl Wisdom