All 32 NFL draft rooms are fully stocked with prospect rankings both by position and regardless of position. General managers package these rankings in different ways to streamline the information and help maintain perspective. This is critical during the stressful and frantic draft weekend.
The following breakdown, which I've dubbed "Rankings Tiers", is a variation that at least two general managers I know keep handy throughout the process. While it is basic in design, the simplest approach is often the best approach and it can be extremely helpful in laying out the true strength of a draft class.
Since the draft has been broken into two days and seven rounds for several years now, it is commonplace for a prospect to be labeled within those tiers. For example, "Joe Smith is a second-rounder" or "John Doe has the look of a Day 2 player." The problem is those tiers are too broad, so they aren't a great deal of help. Breaking a draft board into more specific tiers can help avoid sweeping generalizations and make it easier to quickly separate players.