code: public static String getShipType(Integer ts) {
          if (ts == null)
              return null;
          if (ts < 10 || ts > 99) {
              return "unknown code " + ts.intValue();
          } else {
              int a = ts / 10;
              int b = ts % 10;
              if (a == 3) {
                  return vesselTypes[b];
              } else if (a == 5) {
                  return specialTypes[b];
              } else {
                  return categoryTypes[a] + " - " + cargoTypes[b];
              }
          }
      }
docs: Returns the ship type for given integer. If integer is null then returns
  null.
  
  @param ts
  @return