/** @return String the character encoding of labels in the user interface. 
	 * requestData and html are assumed to be in this charset. 
	 * You need to override and add character conversion if you set this to be different from ValueValidator::getInternalCharset
	 */
	function getLabelCharset() {
		if (isSet($this->labelCharset)) return $this->labelCharset;
		
		return ValueValidator::getInternalCharset();
	}