Nielsen’s firing back at critics, including media execs, who say that the ratings agency fails to count people who watch TV on digital platforms. It can count them — and even include them in audience tallies. But networks and advertisers won’t let them, EVP Global Product Leadership Megan Clarken said today at an NYC summit by the Coalition for Innovative Media Measurement.

“Live viewing on the TV set is in decline — make no mistake,” she says. But the ratings are “an agreed set of rules that the industry came up with” and presented to Nielsen in a 136-page book last revised in 2006. “It’s a very boring read.”

It says that Nielsen only can count viewers for shows that originate on TV. The company can only include people who watch over a certain number of days (live, three or seven). Nielsen has to exclude viewers who watch on a non-TV platform if the program doesn’t have an identical ad load.  And the show needs a linear watermark.

The last criteria makes counting viewers on streaming services a “pain in the ass,” she says. “Netflix and their counterparts strip the watermark.”

The measurement company is working with Adobe on ways to tag shows, which should be ready to go live in Q4.

Nielsen asked the TV industry in November to look at ways to redefine the ratings. “That piece of work is going on” while the company puts together total audience measurements.

“It is not a product. It’s a framework” using a consistent methodology, she says. “We can’t create some sort of Frankenmetric.”

Media execs have taken a lot of shots at Nielsen as they’ve seen ratings fall, especially on cable. For example, Fox COO Chase Carey said in February that “there are issues in terms of the accuracy measurement” as viewing moves “to places that aren’t being captured and adequately measured today.” And Viacom says it hopes to have half of its ad sales be “non-Nielsen dependent” within three years.