Tablespace auto extend AND dba_free_space

Hi

The question that I have is on the relation between the value at dba_free_space and the extensible size of the table space

How can I know the amount of free space that a table space left, take in account the extendable size?

An example:

* First, the actual db data files and their free space:

SQL> select FILE_NAME, MAXBYTES,BYTES,AUTOEXTENSIBLE  from  dba_data_files where tablespace_name='DATA';

FILE_NAME  MAXBYTES               BYTES AUT

------------------- ------------------- ---

/vol01/oradata/COL3PROD/data01.dbf       137438887936        100037361664 YES

/vol01/oradata/COL3PROD/data02.dbf       137438887936         53367341056 YES

The above means, that the first data file has about 34,8 GigaBytes of free space left