I was going to answer this on Rusty's post but it grew to long and I didnt want it to get lost in the off topic route that thread took. With that said, here is information on the list and what it means, basically its like the pup but for non football related injuries.. so after week 6 he can return.
Non-Football Injury (NFI) List
The NFL has a second injury list that is similar to the PUP list, but is based on different timing of injuries. The Non-Football Injury list has rules that closely adhere to those in the Active/PUP and Reserve/PUP, but it is classified differently. The most obvious inclusion would be injuries suffered off the football field (game AND practice fields). If a player gets hurt away from team activities, the team would be eligible to place him on the NFI list.