In reply to Asleep in the backs:
As John said, the obvious choice is a shorter indoor rope and a longer outdoor rope.
But ropes are not cheap. I have used 1 rope for both in the past.
It all comes down to common sense. Inspect the rope yourself and make the call whether you'd trust your life on it.
A quick google search will show you how if you don't know what you're looking for.
For example, this took 10 seconds to find and seems to explain pretty well and the pics definitely helps
http://blog.weighmyrack.com/when-to-retire-your-rope-inspection/
Hope this helps and i'm not teaching you to suck eggs
Post edited at 21:43