These elements are available via the ET family of commands only and are inaccessible from within the GUI:
| SURF251 | 2D Radiosity Surface |
| SURF252 | 3D Radiosity Surface |
| INFIN257 | Structural Infinite Solid (generated via EINFIN) |
| REINF263 | 2D Smeared Reinforcing |
| REINF264 | 3D Discrete Reinforcing |
| REINF265 | 3D Smeared Reinforcing |
| CABLE280 | 3D Cable |