Element codes (ELCODEs) for Elements that are not animals, plants or communities could begin with either an O (for Other) or a G (for Geological) if an agency was interested in tracking them. The codes were fundamentally acronymic and were not maintained by NatureServe Central Sciences. Each agency could assign its own codes, considering the following guidelines for Other Elements:
No guidelines were established for geological features, other than that the ELCODEs should begin with G.