CRLF (\r\n) in PHP's header() function

[bobo]

Why/when does one has to use CRLF's at the end of header in PHP?Here is one example (it's not necessarily correct):\[code\]header("method: POST\r\n");header('Host: '.get_option('transact_url')."\r\n");header('Content-type: application/x-www-form-urlencoded');header('Content-length: '.strlen($transaction)."\r\n");header($transaction."\r\n\r\n");header("Connection: close\r\n\r\n");header("Location: ".$key_client_url."\r\n");\[/code\]