wp-admin/includes/class-ftp.php:463 function systype() { if(!$this->_exec("SYST", "systype")) return FALSE; if(!$this->_checkCode()) return FALSE; $DATA = explode(" ", $this->_message); return array($DATA[1], $DATA[3]); }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/class-ftp.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.