The NFL on Wednesday sent a memo to teams outlining rules for its offseason programs -- rules the league has decided to impose after failing to reach agreement with its players' union on some key aspects.

The parts of the offseason program that are voluntary under the CBA -- everything but the annual mandatory June minicamps -- will remain so. But while the NFLPA has publicly called for the entire offseason to be conducted virtually in light of the ongoing coronavirus pandemic, the league is telling teams that on-field work will be permitted.

Phase 1 of the offseason program, which reflects what the players requested, will run from April 19 through May 14. All meetings will be conducted virtually, and no on-field work will be permitted. The league says it wants to use this phase to focus on vaccine education efforts and making vaccines available to players, team staff and their families as soon as their various local regulations permit.