“The calendar year upfront is a modification of the legacy broadcast year upfront where the same general principles apply – advertising bought and sold in advance,” notes one of the papers, adding: "However, the time frame is shifted to purchase inventory in a specific calendar year upfront with the typical negotiation window occurring in the fall or early winter timeframe.”

The call creates further uncertainty for an upfront advertising season that already has been transformed in terms of its presentations -- which moved from physical events to virtual ones -- and to its timing, which many buyers had already been predicting would shift to the fall or winter.

But in recent weeks, network sales organizations have indicated they are ready to do business as usual, and some have implied they already have negotiations underway. Such posturing is typical for the sell-side, which tries to create momentum for negotiations in order to stampede the market and create perceived demand for its upfront inventory.

While the ANA call did not outline any other specific sweeping changes, it alluded to them.

“Timing is only one of the choices marketers make," ANA Chairman and P&G Chief Brand Officer Marc Pritchard said in a statement, adding: "We need far greater marketplace transparency throughout the media system to enable choices to drive out media waste, improve effectiveness, and dramatically elevate the consumer experience. Only then can we achieve true media transformation and reform.”

He cited several "embryonic initiatives that can revolutionize the industry," including:

• The WFA/ANA collaboration to drive global advances in cross platform measurement.

• The Global Alliance for Responsible Media (GARM) to eliminate harmful content online and alleviate brand safety concerns.

• Privacy for America, which is focused on creating national privacy legislation through the development of one common standard among all states.

• An industry effort to address the transition to a digital ecosystem without third-party cookies.