Watch out when using ‘image’ input types, since the $_REQUEST variables you get vary depending on the user’s browser. Let’s say you’ve got this input field:

<input type="image" src="go.png" value="go" name="pagination_submit" />

In Firefox (and I assume most other logical browsers) you’ll get three $_REQUEST variables from this input: ‘pagination_submit’, ‘pagination_submit_x’, and ‘pagination_submit_y’, where the latter two correspond to the X and Y positions of the part of the image the user clicked.

In Internet Explorer, however – versions 6 through 8 – you’ll ONLY get ‘pagination_submit_x’ and ‘pagination_submit_y’, not the straight ‘pagination_submit’. That’s a real bitch if you ask me… so be careful when testing for the existence of $_REQUEST variables for image input types.