-| Field | Description | Type | Null | Key | Default | Extra |
-| ------- | ------------------------------------------ | ------------------ | ---- | --- | ------- | -------------- |
-| id | sequential ID | int unsigned | NO | PRI | NULL | auto_increment |
-| uid | Owner User id | mediumint unsigned | NO | | 0 | |
-| visible | 1 indicates the member list is not private | boolean | NO | | 0 | |
-| deleted | 1 indicates the group has been deleted | boolean | NO | | 0 | |
-| name | human readable name of group | varchar(255) | NO | | | |
+| Field | Description | Type | Null | Key | Default | Extra |
+| ------- | ----------------------------------------------------------------------------------------- | ------------------ | ---- | --- | ------- | -------------- |
+| id | sequential ID | int unsigned | NO | PRI | NULL | auto_increment |
+| uid | Owner User id | mediumint unsigned | NO | | 0 | |
+| visible | 1 indicates the member list is not private | boolean | NO | | 0 | |
+| deleted | 1 indicates the group has been deleted | boolean | NO | | 0 | |
+| cid | Contact id of forum. When this field is filled then the members are synced automatically. | int unsigned | YES | | NULL | |
+| name | human readable name of group | varchar(255) | NO | | | |