| Abbreviation | Definition |
|---|---|
| OCL | Online Chess League |
| OHSCT | Oregon High School Chess Team |
| OHSCTA | Oregon High School Chess Team Association |
| OMSCC | Oliveira Middle School Chess Club |
| OMSCCB | Oliveira Middle School Chess Club Boosters |
| OOTD | Opening Of The Day |
| OSCF | Oregon Scholastic Chess Federation |
| OTB | Over-The-Board |
| OUCC | Oxford University Chess Club |
| P | Pawn |
| PCA | Professional Chess Association |
| PCC | Pittsburgh Chess Club |
| PCC | play chinese chess |
| PCF | Portland Chess Foundation |
| PCMA | Philippine Chess Masters Association |
| PSCF | Pennsylvania State Chess Federation |
| PXP | Pawn Takes Pawn ( Chess) |
| QB | Queen's Bishop |
| QBP | Queen's Bishop's Pawn |
| QBX | Queen's Bishop takes .... |