private static string FormatSingleRule(Rule rule, string forField) { var tb = new TagBuilder(rule.RuleName); tb.MergeAttributes(rule.ListParameters()); tb.MergeAttribute("forfield", forField); var errorMessage = rule.ErrorMessageOrResourceString; if(errorMessage != null) tb.MergeAttribute("errmsg", errorMessage); return tb.ToString(TagRenderMode.SelfClosing); }