private boolean isTag(String tagUri, String tagLn, String matchUri,
            String matchLn) {
        if (tagUri == null || tagLn == null || matchUri == null
                || matchLn == null) {
            return false;
        }
        // match beginning of URI since some suffix *_rt tags can
        // be nested in EL enabled tags as defined by the spec
        if (tagUri.length() > matchUri.length()) {
            return (tagUri.startsWith(matchUri) && tagLn.equals(matchLn));
        } else {
            return (matchUri.startsWith(tagUri) && tagLn.equals(matchLn));
        }
    }