detecting type of field from $_POST ?

Hi .. i just wonder, is there any way to detecting the type of field (like textarea, button, radio, etc) from $_REQUEST / $_POST ? I need to detect that all .. because I want to put a script that will remove html tag (with htmlspecialchars() function) ... and the problem happen when I use input that produce array (like multiple checkbox will produce an array in $_POST). Is there any way to do this ? thank you -- Best regards, adwinwijaya mailto:adwinwijaya@yahoo.com.au