Files in /tmp directory - Is there any timelimit ?

[Sreeram BS]

Hi,
   I am using FreeBSD 9. I would like to know as to what is the lifetime of
the files in /tmp directory. The general description says that these files
*may* not be preserved across a reboot. By this I interpret that if the
system is not rebooted, then these files will be there forever. But, just
wanted a confirmation to see if there is any lifespan (expiry-time)
attached with these files (ie the system would flush these files after some
days/months etc automatically).

Please inform.

Regards,
Sreeram