I'm pretty sure the second value is the visit flag. If you find this in a save file, it means that the specified zone, object, system, or whatever, has a visit flag of X. The visit flag is what states the visibility you have on it.
Example:
A visit flag of 0 means it is undiscovered, but it will be discovered when found.
A visit flag of 1 means you've discovered it, and it's in the navmap.
I could be wrong, and it could be something else; yet that's the only thing that would make logical sense to me.