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Getting back to the Rebirth engine, simplified mechanics are employed on distant things but the details are a little more nuanced. Due to the focus shifting from sectors to zones, the old IS/OOS terminology doesn't quite fit and although IZ/OOZ is a useful distinction in Rebirth, it isn't quite comparable to the old terminology in terms of the game engine. This is because the engine makes use of "Attention Levels" when deciding how to model what is going on.
During a related discussion, w.evans found the attention levels for us:
"unknown"
"ingalaxy"
"incluster"
"insector"
"visible"
"inzone"
"nearby"
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