| IBASE_DEFAULT | The default transaction settings are to be used. This default is determined by the client library, which defines it as IBASE_WRITE|IBASE_CONCURRENCY|IBASE_WAIT in most cases. |
| IBASE_READ | Starts a read-only transaction. |
| IBASE_WRITE | Starts a read-write transaction. |
| IBASE_CONSISTENCY | Starts a transaction with the isolation level set to 'consistency', which means the transaction cannot read from tables that are being modified by other concurrent transactions. |
| IBASE_CONCURRENCY | Starts a transaction with the isolation level set to 'concurrency' (or 'snapshot'), which means the transaction has access to all tables, but cannot see changes that were committed by other transactions after the transaction was started. |
| IBASE_COMMITTED | Starts a transaction with the isolation level set to 'read committed'. This flag should be combined with either IBASE_REC_VERSION or IBASE_REC_NO_VERSION. This isolation level allows access to changes that were committed after the transaction was started. If IBASE_REC_NO_VERSION was specified, only the latest version of a row can be read. If IBASE_REC_VERSION was specified, a row can even be read when a modification to it is pending in a concurrent transaction. |
| IBASE_WAIT | Indicated that a transaction should wait and retry when a conflict occurs. |
| IBASE_NOWAIT | Indicated that a transaction should fail immediately when a conflict occurs. |