MediaWiki:Apihelp-upload-extended-description
From Hollywood Fans Wiki
Several methods are available:
- Upload file contents directly, using the $1file parameter.
 - Upload the file in pieces, using the $1filesize, $1chunk, and $1offset parameters.
 - Have the MediaWiki server fetch a file from a URL, using the $1url parameter.
 - Complete an earlier upload that failed due to warnings, using the $1filekey parameter.
 
Note that the HTTP POST must be done as a file upload (i.e. using multipart/form-data) when sending the $1file.