That's it Sam!

Note that each chunk is a bit larger than the containing object for there is a 16 byte header in which some info is stored: type, class and size of the chunck, etc.

Free chuncks: they do not contain valid objects.
Recreatable chunks: they contain objects that may be temporaly removed and then recreated.
Freeable chunks: they contain objects need during the session and then freed. They are not recreatable, hence they cannot be temporaly removed from memory.

Sam did not mention the perminant chunks, they contain the so called persistant objects.