DBA_DMT_FREE_SPACE

DBA_DMT_FREE_SPACE describes the free extents in all dictionary managed tablespaces in the database.

Column	Datatype	NULL	Description
`TABLESPACE_ID`	`NUMBER`	`NOT NULL`	Identifier number of the tablespace containing the extent
`FILE_ID`	`NUMBER`	`NOT NULL`	File identifier number of the file containing the extent
`BLOCK_ID`	`NUMBER`	`NOT NULL`	Starting block number of the extent
`BLOCKS`	`NUMBER`	`NOT NULL`	Size of the extent (in Oracle blocks)