Python 700 Starter Kill

I have installed about 5 Python 700 units, but when it comes down to doing the starter kill, i was never sure which wires on the starter kill portion to use.  I always run all three wires to the ignition, cut the starter wire, run the GREEN / WHITE to the keyside and then before i solder, i try to use the green on the motor side, and then the GREEN/ black.  I make sure the car starts when the alarm is unarmed, and doesnt crank when it is armed.  I dont want to keep doing it this way.  I dont understand the difference between normally open and normally closed.  Im assuming I have been using the GREEN/ black (normally closed) wire on the motor side, but i havent reallyt been keepin note.  Can someone please clear this up for me please?

Normally closed is the factory default so green black would be the one that would work right out of the box. Both wires will work but in order to get the green to work you need to change it to that in the programming as far as what the difference is I have no idea so Ill let someone else explain that

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2008 Scion xB
Pioneer AVIC-D3
RF 3Sixty.2 sound processor
Stock speakers (for now ;))

Difference b/w the 2 is
N/c- (default) when ground or 12v is removed from the alarm, you can still start the car
N/o- when the alarm doesnt see ground or 12v, you cant start the car
Say someone cuts the power to your alarm, they can start it if you have it on N/c (loop is closed). But if its N/o they cant start it, they would have to but back the poer and disarm the alarm.

I personally do the N/o just because its an extra feature and easy to install. (dont forget to switch it over first!)

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Note: You Always Dont Get What You Pay For.

Thanks zab I knew thats what it did but you explained it alot better than I ever could have, I would also recommend hooking it up normally open, as Zab said its an extra layer of security and it gives a potential thief a little more trouble.

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2008 Scion xB
Pioneer AVIC-D3
RF 3Sixty.2 sound processor
Stock speakers (for now ;))

Ahhh ok, I get it, thanks a lot.  I guess ill start using that green wire now:)