code: public String getChallengeParam(String path) {
          String result;
          if (path.equals("SegHead.code")) {
              /* this special value is required for HHD1.3, where the segcode
               * can be part of the challenge parameters, but the segcode is
               * not a "lowlevel param", so have to handle this manually */
              result = getHBCICode();
          } else {
              // normal lowlevel param
              String valuePath = this.getName() + "." + path;
              result = this.getLowlevelParam(valuePath);
          }
          return result;
      }
docs: um "besondere Werte" (z.B. sumValues) irgendwie anders zu errechnen