Passed from MultiPart Form or from Hyperlink?

I have a page that can be opened either by the submission of an "enctype=multipart/form-data" form or by the click of a hyperlink.
When I get to the page from the form, I want to use the oReilly MultipartRequest, but when I get to the page through the hyperlink, then there has been no form submission, and I need to NOT use the oReilly MultipartRequest.

So how can I know at the top of the page if I am getting there through a form submission or a hyperlink?
Is there a variable that I can read in that will tell me if there was a form submitted?

Thanks in advance,