DBA_EXTENS

SQL>DESC DBA_EXTENS

 Name                                              Null?    Type
 ----------------------------------------- -------- ----------------------------
 OWNER                                             VARCHAR2(30)
 SEGMENT_NAME                                      VARCHAR2(81)
 PARTITION_NAME                                    VARCHAR2(30)
 SEGMENT_TYPE                                      VARCHAR2(18)
 TABLESPACE_NAME                                    VARCHAR2(30)
 EXTENT_ID                                         NUMBER
 FILE_ID                                           NUMBER
 BLOCK_ID                                          NUMBER
 BYTES                                             NUMBER
 BLOCKS                                            NUMBER
 RELATIVE_FNO                                       NUMBER