note that it does not return the status header

<?php

header('HTTP/1.1 301 Moved Permanently', true, 301);

header('foo: bar');
header('a: b');
header('colon less example');

print_r(headers_list());
?>

Array
(
    [0] => X-Powered-By: PHP/5.4.7
    [1] => foo: bar
    [2] => a: b
)