code: @Override
      protected String getReadOnlyValue(final AbstractUIField _abstractUIField)
          throws EFapsException
      {
          String strValue = "";
          final Object valueTmp = _abstractUIField.getValue()
                          .getReadOnlyValue(_abstractUIField.getParent().getMode());
          if (valueTmp instanceof Number) {
              strValue = String.valueOf(valueTmp);
          } else {
              strValue = valueTmp == null ? "" : String.valueOf(valueTmp);
          }
          return strValue;
      }
docs: {@inheritDoc}