Washington ? The CEOs of Google and Verizon outlined a proposal Monday that they hope will serve as a template for so-called network neutrality: It would forbid Verizon from prioritizing traffic on the Internet, but would allow firms with specialized products, such as 3-D video or health care monitoring systems, to purchase faster speeds for their offerings.

The announcement by Google CEO Eric Schmidt and Verizon CEO Ivan Seidenberg is a milestone in the intensifying debate over how to maintain the Internet as an open platform. As the Internet evolves, especially as a medium for video, critics worry that broadband network owners such as Verizon and AT&T will be increasingly tempted to prioritize Web traffic based on profit motives.

That could happen by reserving faster speeds for websites that pay for the privilege, or slowing the delivery of sites that compete with the broadband providers’ own offerings.

In a conference call Monday, Schmidt and Seidenberg said the firms’ announcement is meant to allay such concerns. Any lawful Internet content will be treated equally over Verizon’s broadband network, Seidenberg said, and the company will not engage in “paid prioritization” of traffic, Seidenberg said.

But two other elements of the deal are certain to draw close scrutiny in the coming days and weeks. First, the ground rules would not apply to wireless networks, meaning Verizon could discriminate against certain types of applications over the network that delivers Web data to smart phones. The firm would only have to disclose how it was managing its wireless network.

The provision allowing Verizon to sell “fast lanes” for specialized services, which Seidenberg said would have to be distinguishable from anything currently carried over the Internet, is also likely to arouse controversy. Schmidt said Google would not attempt to purchase such special access for YouTube videos or other Google content.

Federal Communications Commission Chairman Julius Genachowski’s attempt to enshrine rules was blocked by a federal court ruling this spring that the FCC lacked authority over broadband.

Genachowski responded by trying to organize a series of closed-door negotiations among companies on opposing sides of the net neutrality issue. But those talks broke down last week, and on Monday Google and Verizon stepped into the void with a proposal intended to guide members of Congress looking at possible legislation.

“There is no business arrangement,” Seidenberg said, calling the announcement instead a “joint effort by two companies to offer suggestions to the public policy arena.”