Expiration stored on sql

I have a doubt... I'm using freeradius from Ubuntu 8.04. if i have to store an expiration date i stored some thing like that: username Attribute op Value someuser Expiration := 24 Nov 2010 13:58 I have a check to a Wifigator server and i see that they stored it as a timestamp (in secondes)... Who is right? who is wrong? regards