[NTLDR]

PHP Code:

<?php

if ($a) {
    require_once('./includes/functions_bbcodeparse.php');
    $b = parse_bbcode($b);
}

$c = parse_bbcode($c);
?>

Take the above as an example, if $a is false then you'll get a fatal error on line 8, because the file hasn't been required, where as if $a is true you won't get an error.

The alot of the functions files arn't required unless they are needed at a certain point to improve speed.