function checkEnter(e){ //e is event object passed from function invocation

	var characterCode // literal character code will be stored in this variable

	if(e && e.which){ //if which property of event object is supported (NN4)
		e = e;
		characterCode = e.which; //character code is contained in NN4's which property
	} else {
		e = event;
		characterCode = e.keyCode; //character code is contained in IE's keyCode property
	}

	if(characterCode == 13){ //if generated character code is equal to ascii 13 (if enter key)
		submitform(); //submit the form
		return false;
	} else {
		return true;
	}

}

function submitform() { document.thisPageForm.submit(); }