Header format for multipart/formdata file upload

[RobBroekhuis]

I'm trying to write a script for automatic uploading of file data to a remote server. I'm using PHP with cURL support; for ordinary POST forms, I just format the header data as if it were a querystring. Where can I read about how to format a header for the file upload request?
Thanks for your help!
Rob

[lobo235]

There is probably an RFC that describes how it works. I would search on Google for 'http file upload rfc'