“Gray” vs “Live” IP – Explanation Request

I’m probably a little over my head right now but feel certainly someone can help with an explanation.

I am in the process of putting a new server in place and am being asked if I am going to require a “Live IP” or “Gray IP”

I’m far from new to server/workstation work however I must admit that in all my dealings I have not come across this terminology nor do I understand what is truly being asked.

Is there someone that can possibly give me a clear explanation. Following that I would also appreciate any pointers to additional information so that I might have a better understanding.

Thanks.

Richard