DBA_DMT_USED_EXTENTS

DBA_DMT_USED_EXTENTS describes the extents comprising the segments in all dictionary managed tablespaces in the database.

Column	Datatype	NULL	Description
`SEGMENT_FILEID`	`NUMBER`	`NOT NULL`	File number of the segment header of the extent
`SEGMENT_BLOCK`	`NUMBER`	`NOT NULL`	Block number of the segment header of the extent
`TABLESPACE_ID`	`NUMBER`	`NOT NULL`	Identifier number of the tablespace containing the extent
`EXTENT_ID`	`NUMBER`	`NOT NULL`	Extent number in the segment
`FILEID`	`NUMBER`	`NOT NULL`	File identifier number of the file containing the extent
`BLOCK`	`NUMBER`	`NOT NULL`	Starting block number of the extent
`LENGTH`	`NUMBER`	`NOT NULL`	Number of blocks in the extent