There's been a lot of PUP list references in the news today so I thought I'd dust off some clarification of one of the most misunderstood eligibility rules in the NFL.

First and foremost, there are two PUP lists.

The PUP list that you may have seen in today's news stories refers to the 'Active PUP' list.

The Active PUP is for players that have some form of injury that will prevent them from starting training camp.

If placed on Active PUP, a player can rehab and participate in team meetings but cannot practice.

A player has to be placed on Active PUP before he begins training camp, so that's why you're seeing the stories popping up now.

A player on Active PUP can be removed from the list at any time during camp.

A player on Active PUP counts against the league mandated roster limit (currently 80).

And one of the most important rules, a player must be on Active PUP in order to be considered for Reserve PUP.

At the end of preseason, if an Active PUP player is still several weeks away from being able to play, the team may place him on Reserve PUP.

Reserve PUP players are not eligible to play for the first six weeks of the season.

Reserve PUP players do not count against the 53 man roster.

Reserve PUP players have a three week window after Week 6 to practice with the team but a roster decision must be made, either to activate to the 53 or to IR the player, within that timeframe.

If a player is activated off the Reserve PUP following Week 6, a roster move is required to make room . That's what happened on October 17, 2008 when Dunta Robinson was activated from Reserve PUP and Chris Taylor was placed on injured reserve.

From what I've been reading in various news sources, I would imagine the only Active PUP candidates for the Texans are Antwaun Molden and Travis Johnson.

If Molden doesn't start training camp on Active PUP, it's good news since Active PUP is typically a hedge against the possibility that the player won't be ready to go during the first few weeks of the regular season.