code: public void mergeVertexDescription(VertexDescription src) {
  		_touch();
  		if (src == m_description)
  			return;
  
  		// check if we need to do anything (if the src has same attributes)
  		VertexDescription newdescription = VertexDescriptionDesignerImpl.getMergedVertexDescription(m_description, src);
  		if (newdescription == m_description)
  			return;
  		
  		_assignVertexDescriptionImpl(newdescription);
  	}
docs: Merges the new VertexDescription by adding missing attributes from the
  src. The Geometry will have a union of the current and the src
  descriptions.
  @param src VertexDescription to merge.