Offseason practices: QB & Receiver timing

[Bill B]

Just wondering if anyone knew the NFL rules on what types of practices are allowed in the offseason with regard to qb and recievers? I know that NFL regulates the amount of full team practices and that teams get by with offeseason voluntary workouts, but is there a restriction on the amount of interaction between a qb coach and the qb/recievers? The reason I bring this up is will Jason Campbell be allowed to work with his full reciver set during the offseason with a qb coach/Gibbs/Saunders by his side givning instruction or is this type of activity not allowed?