forward arguments in upload module

[vetri]

hi all,

    uploading files via nginx is awesome .i am sending query arguments
in post operation which will be passed to backend server.i want to
append one more key value pair to that query arguments  to send into
backend server(own key value will be taken from program).if i want to do
like this which part of the program i should concentrate to append my
own arguments to that query arguments and send  to backend server.if
someone has code knowledge just help me where to concentrate and help me
do this possible 

Thanks in Advance

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,205669,205669#msg-205669