So you're wondering what use is all about?
http://search.cpan.org/dist/perl-5.10.0/pod/perlfunc.pod#use
http://search.cpan.org/dist/perl-5.12.0/pod/perlfunc.pod#use
http://search.cpan.org/dist/perl-5.14.0/pod/perlfunc.pod#use
http://search.cpan.org/dist/perl-5.16.0/pod/perlfunc.pod#use

As Tutorials: Basic debugging checklist teaches, use B::Deparse to see how perl interprets the code

$ perl -MO=Deparse -le " use 5.010; "
BEGIN { $/ = "\n"; $\ = "\n"; }
sub BEGIN {
    require 5.01;
}
-e syntax OK
[download]

Hmm, try again :)

$ perl -MO=Deparse -le " use 5.010; state $fudge; "
BEGIN { $/ = "\n"; $\ = "\n"; }
sub BEGIN {
    require 5.01;
}
no feature;
use feature ':5.10';
state $fudge;
-e syntax OK
[download]

There you have it, state, feature
http://search.cpan.org/dist/perl-5.10.0/lib/feature.pm
http://search.cpan.org/dist/perl-5.12.0/lib/feature.pm
http://search.cpan.org/dist/perl-5.14.0/lib/feature.pm
http://search.cpan.org/dist/perl-5.16.0/lib/feature.pm