Parlay question

[freebie]

Can someone explain to me what do "open spot" on parlay mean?

I see it on Cris' parlay option for 1-2 open spot, but never understood the meaning of it.

[Max Levine]

As an example, you can take a 3-team parlay but only pick 2 games. If they both win, you add 1 more game later on to complete your parlay. Some books limit your time to a week, some to a month to complete your parlay.

Max