/** Pattern for parsing allow records. */
    protected static final Pattern ALLOW_RECORD = Pattern.compile("^allow:\\s*([^\\s]*)\\s*$", Pattern.CASE_INSENSITIVE);

    /** Pattern for parsing crawl-delay records. */
    protected static final Pattern CRAWL_DELAY_RECORD = Pattern.compile("^crawl-delay:\\s*([^\\s]+)\\s*$", Pattern.CASE_INSENSITIVE);

    /**
     * Pattern for Sitemap record.
     */