function isEnter(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)
		characterCode = e.which; //character code is contained in NN4's which property
	}
	else{
		characterCode = event.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)
		return true;
	}
	else{
		return false;
	}
}