The local() function will only work on existing package variables. The reason being is that it localises the given variable(s) to the current scope e.g

$foo = "main scope";
{
    local $foo = "temp scope";
    print "\$foo is $foo\n";
}
print "\$foo now $foo\n";
__output__
$foo is temp scope
$foo now main scope
[download]

This is handy for some of perl's cruftier globals such as $/ and $".
HTH

broquaint