| C5 | ⊕ 1988 | ↓ ↑ ⊕ Specialised Languages | ⊕ RETE and production | ⊕ United States | C based version of OPS-5 |
| OPSJ | ⊕ 1988 | ↓ ↑ ⊕ Specialised Languages | ⊕ RETE and production | ⊕ United States | Production system |
| RDL1 | ⊕ 1988 | ↓ ↑ ⊕ Specialised Languages | ⊕ RETE and production | ⊕ France | |
| RPL | ⊕ 1988 | ↓ ↑ ⊕ Business Data Processing | ⊕ RETE and production | ⊕ United States | The Relational Production Language |