If you create a form which is a get, not post you will see that the url string just gives the name and the value.
If it's coming from your form you should now at design time therefore your script would know. If the problem is that you have a several forms ie page 1 collects name and address, page 2 collects other info, page 3 collects payment info then have a variable called "pageno" and make assumptions based on the pageno.
Guess I've never needed to know what type of form control I've used. Maybe if you post more info I might understand the "business problem" you are trying to solve.
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