code: protected void startNonVisibleElement() throws SAXException
      {
          if (shouldRemoveWhiteSpaces()) {
              cleanContentLeadingSpaces();
              cleanContentExtraWhiteSpaces();
  
              if (getContent().length() > 0) {
                  sendPreviousContent(false);
  
                  fPreviousInlineText.append(getContent());
  
                  if (getContent().charAt(getContent().length() - 1) == ' ') {
                      fPreviousContent = getContent().toString();
                  } else {
                      sendCharacters(getContent().toString().toCharArray());
                  }
              }
  
              // The is some text ending with a space before the non visible
              // element. The space will move after the element if it's needed (if
              // the element is followed by inline text);
              if (fPreviousContent != null) {
                  sendCharacters(fPreviousContent.toCharArray(), 0,
                      fPreviousContent.length() - 1);
                  fPreviousContent = " ";
              }
          } else {
              // Send current content
              sendCharacters(getContent().toString().toCharArray());
          }
  
          getContent().setLength(0);
  
          // Do not clean white spaces when in non visible element
          ++fNoCleanUpLevel;
      }
docs: Append an non visible element.