| ALGOL 68 Revised | ⊕ 1975 | ↓ ↑ ⊕ Numerical Scientific | ⊕ True ALGOL68s | ⊕ International | |
| ALGOL 68C | ⊕ 1975 | ↓ ↑ ⊕ Numerical Scientific | ⊕ True ALGOL68s | ⊕ United Kingdom | Cambridge Algol 68 |
| Algol H | ⊕ 1975 | ↓ ↑ ⊕ Experimental and other | ⊕ True ALGOL68s | ⊕ United Kingdom | Proposed extensions to the mode system of Algol 68 |