TSTriple() usage

[jimmymagemtek]

Hi Sir,
As the line of code below,

    ts_sda = TSTriple(1)

ts_sda then has three attributes:
ts_sda.i
ts_sda.o
ts_sda.oe
Why do I see in some example code that ts_sda.oe is used as the output port, instead of ts_sda.o ?

What do they really represent respectively?
I can't tell even after see the definition in specials.py

Thanks.
Jimmy