Header order question in PHP (and HTTP in general)

[SL7]

Is there a particular order in PHP to set HTTP headers with the header() function ?I mean for example must I call header('Content-Language: en'); before header('Content-Type: text/plain'); or whathever order will be OK.My guess is that order isn't important as long as all he headers are set before any content outputted, but I just want to be sure that's the case...