Microsoft Jet adds several system tables to the database when the database is replicated. These tables are system tables, which are not normally visible to users and cannot be manipulated by programmers. The following table describes the system tables added to the database during replication.
| Name | Description |
| MSysErrors | Identifies where and why errors occurred during data synchronization. This table appears in all members of the replica set and is empty when all errors have been resolved. |
| MSysExchangeLog | Stores information about synchronizations that have taken place between this member and other members of the replica set. This is a local table. |
| MSysGenHistory | Stores a history of generations of updates. It contains a record for each generation that a replica knows about. It is used to avoid sending common generations during synchronizations and to resynchronize replicas that are restored from backups. This table appears in all members of the replica set, but it is merged by a process slightly different from that used with normal replicated tables. |
| MSysOthersHistory | Stores a record of generations received from other replicas. It contains one generation from every message seen from other replicas. |
| MSysRepInfo | Stores information about the entire replica set, including the identity (GUID) of the Design Master. It contains a single record. This table appears in all members of the replica set. |
| MSysRepLock | Stores information about locking conflicts encountered during synchronization. |
| MSysReplicas | Stores details (such as the replica ID and path) of all replicas in the replica set. This table appears in all members of the replica set. |
| MSysSchChange | Stores design changes that have occurred in the Design Master so that they can be dispersed to any member of the replica set. The records in this table are deleted periodically to minimize the size of the table. |
| MSysSchedule | Stores information for scheduled synchronizations. The Synchronizer for a local replica set member uses this table to determine when the next synchronization with another Synchronizer should take place, and how to synchronize data and design changes with the other Synchronizer. |
| MSysSchemaProb | Identifies errors that occurred while synchronizing the design of the replica. This table exists only if a design conflict has occurred between the user’s replica and another member of the replica set. This is a local table. |
| Name | Description |
| MSysSidetables | Identifies the tables that experienced a conflict and the name of the conflict table that contains the conflicting records. This table exists only if a conflict occurs between the user’s replica and another member of the set. This is a local table. |
| MSysTableGuids | Stores the name of all replicated tables and their GUIDs. TableGUIDs are used in tables such as MSysTombstone as a reference to a table name stored in this table. This allows efficient renaming of tables. In addition, this table includes the level number used for ordering tables so that updates can be processed efficiently when referential integrity is enforced. This is a local table that is updated by the tracking layer in the Design Master and, as part of the processing of design changes, in all other members of the replica set. |
| MSysTombstone | Stores information about deleted records, and allows deletes to be dispersed to other replicas. This table appears in all members of the replica set. |
| MSysTranspAddress | Stores addressing information for the Synchronizer and defines the set of Synchronizers known to this replica set. This table appears in all members of the replica set. |
| MSysTranspCoords | Stores the display layout of the Synchronizers and replicas in the synchronization window of the Replication Manager. |