/** Query parameter name for main search query. */
    public static final String OPTION_QUERY_Q = "q";

    /** Query parameter name for constraint query. */
    public static final String OPTION_QUERY_CQ = "cq";

    /** Query parameter name for optional query. */
    public static final String OPTION_QUERY_OQ = "oq";

    /** Query parameter name for negative query. */
    public static final String OPTION_QUERY_NQ = "nq";