Another development was the insight into the delimitation of the concept of 'plant'. Gradually more and more groups of organisms are being recognised as being independent of plants. Nevertheless, the formal names of most of these organisms are governed by the (ICN), even today. Some protists that do not fit easily into either plant or animal categories are treated under either or both of the ICN and the ICZN. A separate "Code" was adopted to govern the nomenclature of Bacteria, the "International Code of Nomenclature of Bacteria".