Just been informed that DE Chris Cooper has an unspecified leg injury and DT Larry Tripplett a knee problem that forced them out of practices today and will keep them from playing in the scrimmage tomorrow.

Both are expected back next week. I had forgotten to mention P Ryan Plackemeier in the players that are out two posts ago, and he could start kicking in practice next week.

The Seahawks beat writers just met with some NFL officials who are in camp to work practices and who will work the scrimmage tomorrow at Qwest Field. Referee Peter Morelli, head linesman George Hayward, back judge Kirk Dornan and first-year side judge Greg Wilson showed a video outlining the officials' points of emphasis this season. Highlights:

-The force-out rule on catches will no longer be enforced. It's an incomplete pass unless the receiver gets both feet inbounds first or is ruled to be carried out after making the catch clearly inbounds.

-No more 5-yard facemask penalties. All are 15 yards.

-The defense can now have a player wear a speaker in his helmet, just like a quarterback, to hear signals. One starter and one backup can do so but cannot be on the field at the same time and must report themselves to the referee.

-A snap untouched is ruled as a backward pass and can be advanced as a fumble. All muffed handoffs and forward handoffs that are fumbled can be advanced by the defense if it recovers.

-Teams who win the opening coin toss can now choose to defer their option to kick or receive to the start of the second half, just like in college.

-An offensive player who sticks his arm out can make contact with a defender's facemask, but if he grabs it it is a 15-yard penalty. Officials will be watching this more closely.

At some point this afternoon the media will find out why DE Chris Cooper and DT Larry Tripplett did not practice this morning. They are the latest two players who are out, joining LBs Wesly Mallard and Will Herring, G-C Chris Gray, C Chris Spencer, WR Deion Branch, DT Marcus Tubbs, WR Courtney Taylor, TE Jeb Putzier and DT Red Bryant.

Bryant, the team confirmed, is to have knee surgery. UPDATE: Bryant had the surgery today, performed by team doctor Ed Khalfayan at the Seattle Surgery Center. He was on crutches today and will miss four or five weeks.

The center-QB exchange was a big issue this morning. No. 1 center Steve Vallos, who is there because Spencer and Gray are out, accidentally tripped QB Matt Hasselbeck on a play coming out from under center, which had Hasselbeck limping for several plays thereafter. No. 2 center Mansfield Wrotto, a true guard, struggled on the exchange with QB Seneca Wallace three times.

MLB Lofa Tatupu was not in on team drills but did participate in individual stuff. And both the No. 1 and No. 2 offenses drove for touchdowns in the final drill of the morning. FB Leonard Weaver caught a screen pass on third-and-goal and ran it in, and TE Joe Newton made a TD grab on fourth-and-goal.

That's what coach Mike Holmgren announced this morning in an interview on KJR-AM. Bryant, the rookie fourth-round pick from Texas A&M, will miss four or five weeks, Holmgren added.

Bryant underwent tests Thursday to determine the severity of an injury to his left knee after missing practice Thursday. Holmgren said Bryant has cartilage damage but was not specific.

Bryant's loss is critical because the Seahawks are already without their other big and tall body in the middle of the defensive line, Marcus Tubbs, at least for the time being. The timing of the injury for Bryant means he could be ready to play by the first week of the regular season, but will miss invaluable time in exhibition games.

Holmgren also updated the injury and rehabilitation status of some other players. C Chris Spencer and Tubbs are expected to be able to practice next week, Spencer perhaps on Monday. C-G Chris Gray has gone home to Alabama for a few days but is also expected to be able to practice Monday. P Ryan Plackemeier could start punting next week.