function checkPrefix(el) {
	if (!el) return;
	if (el.options[el.selectedIndex].value=='0') {
		// 'other' selected... means that the select-field has to be changed to a text-field
		var inputField = document.createElement('input');
		inputField.type='text';
		inputField.className='prefix';
		inputField.value='00';
		inputField.onfocus=function(){ unRed(this);};
		el.parentNode.insertBefore(inputField,el);
		el.parentNode.removeChild(el);
		inputField.id=el.id;
		inputField.name=el.name;
		inputField.focus();
	}
}

function doRed(el) {
	el.className = el.className.replace('error','');
	el.className = el.className + ' error';
}

function unRed(el) {
	el.className = el.className.replace('error','');
}