Does flash always post a "Filename" parameter when doing a file upload?

I have tried two flash upload components, swfupload and uploadify, and both seem to generate POSTs with a "Filename" parameter. My problem is that the service I'm posting to has a strictly specified set of allowed parameters and Filename is not one of them.

So, is it at all possible to remove this 开发者_开发知识库parameter from the post?

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A quick look at the docs reveals that you can change the uploadDataFieldName, which is by default "Filedata", by setting the second parameter of the upload() method. Docs doesn't say anything about the Filename parameter though, so I guess that's a no.