Hopefully, if you made contact with this company they answered your question if you asked... That's the importance of asking the author what is meant and not leave it up to others interpretation. I know what it means, however, as nurses we need to ask the right questions of the right people for the right reasons, at all times. Good luck.
I was looking too and I called the human resource people. It stands for eligible for night shift bonus which is extra vacation or extra cash at end of a year if you work nights. I will like this because I am a night owl anyways.