it means  how much you can EXTEND DB  the database    you assign space to
your Database... but you don't really use it till you EXTEND it...  the Max
extend is how much bigger you can increases the size of the DB with the
current volumes assigned.....   max reduction is how much unused space in
the db and be REDUCED  or given back to the DB volumes....

The point of this is that you can assign and make available a lot of DB
space...   put only use & backup what you need

Rich Taft
Ricoh corp