fragment question

Hi,
After running the script below, can any body tell me at what point the FSFI is not allowed to fall? I mean at what point is the FSFI considered to be accepted and unacceptable

select tablespace_name,
sqrt(max(blocks)/sum(blocks))* (100 /sqrt(sqrt(count(blocks)))) FSFI
from dba_free_space
group by tablespace_name
order by 1;

This formulation comes from Loney and Theriault's DBA Handbook. They say over 30 should be OK

thanks for that

What is FSFI BTW ?

Thanks.

Free Space Fragmentation Index if I'm not wrong.