Adds a POST field with specified name and value to the request submitted to the server.
getImageUploader("ImageUploaderID").AddField(Name, Value);
Name of the POST field (an analogue to the name attribute of an <input> HTML element).
If you try to add several fields with the same name, the latest one will overwrite the previous value.
Alternatively you can attach an additional form to the request. Use the AdditionalFormName property to do that.