So many shows are now recorded on DVRs and viewed later, the networks and advertisers are now working on a formula to account for deferred viewing, according to the New York Times. "Live plus 72 hours" is the current thinking.

With DVR penetration at 17 percent of American homes, and reaching 25 percent in some large cities, the networks have been wanting to count shows watched as much as a week later in their ratings. The higher the ratings, the more they can charge advertisers.

The advertisers, on the other hand, wanted accounting only for live viewers. They claim that many commercials are time sensitive, for example weekend sale announcements. [They also know that many of those commercials are skipped when the show is played back later.]

"The compromise on live plus three [days] was discussed yesterday by executives of CBS at a news conference to introduce their prime-time schedule for 2007-8," Stuart Elliott wrote. "Executives at ABC, who presented their schedule on Tuesday, also said they believed that live plus three would become the common currency for upfront negotiations." Jo Ann Ross at CBS said that a lot clients and agencies have already accepted the Live plus 3 [day] standard.

What’s driving all this is research showing the rate of growth of DVRs. David F. Poltrack, chief research officer at CBS, said the DVR penetration will be about 21 percent nationally by the fourth quarter and in the high 20s in the spring of 2008.

As for the agreements, the networks are taking a moderate approach because they can see the DVR trend. "We want the advertisers to be comfortable," Mr. Poltrack said. "This year, slow and steady may win the race."