ParPort output low - hi-Z or ground?

Spent a day drawing up an optoisolation scheme for the parallel
port. I know the inputs go between +5V and 0V but, when you set an
output to low, is it connected to ground or does it go hi-Z?

Silly me, I was thinking in terms of sourcing current from the port
(OUTput...) and getting fancy with transistors. Just as I finished
the drawing (As usual!) I realized that its TTL and TTL is much
better at sinking. If it goes to ground then a couple resistors and
1N4148's are all I need to drive the opto-leds.