| OWNER | CHAR(3) |  | Owner of the undo tablespace | 
| SEGMENT_NAME | VARCHAR2(30) | NOT NULL | Name of the undo segment | 
| TABLESPACE_NAME | VARCHAR2(30) | NOT NULL | Name of the undo tablespace | 
| EXTENT_ID | NUMBER |  | ID of the extent | 
| FILE_ID | NUMBER | NOT NULL | File identifier number of the file containing the extent | 
| BLOCK_ID | NUMBER |  | Start block number of the extent | 
| BYTES | NUMBER |  | Size of the extent (in bytes) | 
| BLOCKS | NUMBER |  | Size of the extent (in blocks) | 
| RELATIVE_FNO | NUMBER |  | Relative number of the file containing the segment header | 
| COMMIT_JTIME | NUMBER |  | Commit time of the undo in the extent expressed as Julian time. This column is deprecated, but retained for backward compatibility reasons. | 
| COMMIT_WTIME | VARCHAR2(20) |  | Commit time of the undo in the extent expressed as Wallclock time.This column is deprecated, but retained for backward compatibility reasons. | 
| STATUS | VARCHAR2(9) |  | Transaction Status of the undo in the extent: |