// Form, acciones
function rule_mail(elemento, error_message)
{
		var s = document.getElementsByName(elemento)[0];
    var filter=/^[a-zA-Z0-9]+[_a-zA-Z0-9-]*(\.[_a-z0-9-]+)*@[a-zA-Z0-9]+(-[a-zA-Z0-9]+)*(\.[a-zA-Z0-9-]+)*(\.[a-z]{2,4})$/;
    if (!filter.test(s.value)) {
    	return error_message;
    }
    return '';
}
function rule_required(elemento, error_message)
{
		var s = document.getElementsByName(elemento)[0];
    if (!s.value || s.value==0 ||s.value == '') {
    	return error_message;
    }
    return '';
}
function rule_iguales(elemento, error_message, elem1, elem2)
{
		var val1 = document.getElementsByName(elem1)[0].value;
		var val2 = document.getElementsByName(elem2)[0].value;
    if (val1 != val2) {
    	return error_message;
    }
    return '';
}
function rule_callback(elemento, error_message, nombre_func)
{
		var val = document.getElementsByName(elemento)[0].value;
    if (!eval(nombre_func+'("'+val+'")')) {
    	return error_message;
    }
    return '';	
}
function rule_checked(elemento, error_message)
{
		var s = document.getElementsByName(elemento)[0];
    if (!s.checked) {
    	return error_message;
    }
    return '';
}