Jackson's reporting deadline is earlier because the Chargers elected to place him on the roster exempt list, meaning Jackson must sit out three unpaid games before he is eligible to receive the necessary six paid games to earn his sixth accrued season.

Neither Jackson nor Mankins could be reached for comment. Their agents, Neil Schwartz (Jackson) and Frank Bauer (Mankins), declined comment.

Jackson and Mankins were among the players caught in significant changes because of an uncapped year that moved unrestricted free agency from four years to six years. Jackson and Mankins became part of a large class of restricted free agents when their contracts expired after their fifth season (2009). Both declined to sign their restricted free agent contract tenders, a requirement before players can report to their teams.

In a related development, NFLPA general counsel Richard Berthelsen recently sought clarification on the reporting dates because the NFL constitution has a bylaw that states clubs have an option not to reinstate a player who reports after Tuesday's trade deadline. That created a potential conflict with the labor agreement, which states that a player who has not signed a contract by the Tuesday following the 10th week of the regular season would be ineligible to play that year.

Jeffrey Kessler, chief outside legal counsel for the NFLPA, confirmed that he was asked by the union to clarify the potential conflict.

"The issue arose, we had a discussion and the league quickly agreed that the CBA supersedes the constitution on any potential conflicting provision," Kessler said.

"Yes, that's correct," confirmed NFL spokesman Greg Aiello via e-mail. "In the CBA, a restricted free agent has the right to accept his tender and report to the club any time up until the Tuesday after week 10 (Nov. 16, 4 p.m. ET) of the regular season, whether or not the club requests or agrees to his reporting."

Berthelsen asked Kessler to get a clarification because the league constitution that governs its 32 member clubs addresses the status of specific absent players in bylaw 17-13: "All players in categories of Reserve/Retired, Reserve/Did Not Report, and Reserve/Veteran Free Agent asked to Re-Sign will continue to be prohibited from being reinstated in the last 30 days of the regular season. Additionally, no player in such category shall be reinstated between the trade deadline of the applicable season and the normal 30-day deadline unless the club initiates the reinstatement request and the commissioner approves it."

The union wanted pre-emptive clarification in case one of the clubs attempted to use the constitutional bylaw to prohibit Jackson and Mankins from reporting because it did not want to have file a grievance to a Special Master, creating further delay.

Kessler would not confirm that the union has recommended Jackson and Mankins report in time to get their sixth accrued season in the event there is no labor agreement. That would allow teams to impose the restricted contract tenders on them in 2011, per the current CBA.

The same sources strongly reaffirmed Jackson and Mankins will follow the NFLPA's recommendation and report to the Chargers and Patriots by their respective deadlines to ensure unrestricted free agency in 2011.

Jackson would miss his unpaid games of Oct. 31 (vs. Tennessee), Nov. 7 (at Houston) and Nov. 22 (vs. Broncos) because of his roster-exempt status before he can be paid for the final six games, starting Nov. 28 (at Indianapolis). The Chargers have a bye in Week 10.

Mankins would have to report by the final deadline of Nov. 16, making him eligible to be paid and play in the final seven games because the Patriots had their bye in Week 5. The Patriots opted not to place him on the roster exempt list, as the Chargers did with Jackson.

Both players can be traded by Tuesday's 4 p.m. deadline if they are willing to sign their contract tenders. Jackson would have to sit out the first three games with his new team under his roster-exempt status before being eligible to play.

Jackson was able to serve a three-game suspension to begin the season for violation of the personal conduct policy after being convicted of a second DUI even though he is not under contract.

The Chargers receiver, a Pro Bowl selection in 2009, is not facing an automatic year suspension under the substance abuse policy -- the next alcohol or drug violation under a specific disciplinary scale, would cost Jackson four game checks. Jackson is being tested randomly several times per month under the policy.

By Jackson and Mankins earning a sixth accrued season, the only way the Chargers and Patriots can restrict their free agency in 2011 would be to place a franchise tag on them next February at a considerably higher guaranteed value than the restricted contract tenders. A transition tag also would be available for the Chargers and Patriots instead of the franchise tag, but the teams would not receive any draft pick compensation and would have only right of first refusal on any contract the players signed with another team.

Chris Mortensen is a senior NFL analyst for ESPN.com.