What is PI by OSIsoft

Hello All:

I've been tasked with assisting in the implementation of PI by OSI
soft. The people giving the presentation gave me some info that makes
it sound like it is a system with facility for tuples with exactly 3
fields, one of which is a time stamp. Any one know much about this
system? Is it an RDBM?, object style thing?, some kind of abstraction
layer? The PI web site is heavy on marketing (what it can do for me)
and light on mechanics (how it does it). I have a _very_ basic
understanding of databases.

Cheers and Thanks.

John Eggert.