Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             reactive intermediates
               Class cations [X+]
                 Class amidium ions
                   1 Class carboxamidium ions [RC(OH)=N+R2 <-> RC(=O+H)NR2 or RC(=O)N+R3]