*/
    @ValidateTypeFailure
    public Integer pn;

    /**
     * Similar document hash for finding related documents.
     */
    @Size(max = 1000)
    public String sdh;

    /**
     * Parameter to control tracking of total hits in search results.
     */
    @Size(max = 100)
    public String track_total_hits;

    /**
     * Default constructor for SearchForm.

    /**
     * Encodes a string for similar document hash processing.
     *
     * @param input the string to encode
     * @return encoded string, or the original input if blank
     */
    public static String sdh(final String input) {
        if (StringUtil.isBlank(input)) {
            return input;
        }
        return ComponentUtil.getDocumentHelper().encodeSimilarDocHash(input);
    }

    /**

        public SearchRequestType getType() {
            return SearchRequestType.JSON;
        }

        @Override
        public String getSimilarDocHash() {
            return request.getParameter("sdh");
        }

        @Override
        public HighlightInfo getHighlightInfo() {
            return ComponentUtil.getViewHelper().createHighlightInfo();
        }
    }

    /**