I have a php file containing a form which utilisies an image as a submit button in the following format.

<input type="image" name="newcustomer" src="images/newcustomer.gif" alt="add a new customer record">

When the button is clicked, the form posts back to the same page and some checks are made to determine if
the button was the cause of the post as shown below...

	if(isset($HTTP_POST_VARS["newcustomer.x"])) {
		$editmode = true;
		$customerid = -1;
	} else {
                             $editmode = false;
              }

When the above code is executed, $editmode always comes out as false. However, on outputing the value of the 
POST array for 'newcustomer.x' nothing is displayed. I have also tried to use GET as the form method and printed out the contents of the GET array for 'newcustomer.x' and it is also blank. 

To follow this up I have also tried to make requests to a generic PHP file which prints out the contents of the $HTTP_GET_VARS array and can always reproduce the fact that any parameter containing a '.' within the name
are never stored.

Its possible that this problem could lie in the array structure itself rather than the request processing, but I am not sure.