The Interactive Advertising Bureau has released for public comment an updated version of its Standard Ad Unit Portfolio designed to reflect brands' needs to reach consumers across multiple devices.

The overhaul will provide new standards for ad characteristics such as file size, weights and aspect ratios in a world where the size and shape of screens continues to proliferate.

"It's a pretty big change for the IAB because we are moving away from fixed units and toward a more responsive model," said Alanna Gombert, general manager at the IAB Tech Lab, which spearheaded the effort. "The ad units will adjust themselves based on screen size."

The revised portfolio also introduces guidelines for experiences like virtual reality, vertical video, emoji, stickers and 360-degree video ads. IAB members were very adamant on focusing on emerging technologies, Ms. Gombert said.

All of the units will comply with the bureau's "LEAN" principles, introduced last year in a bid to improve the consumer experience online and undermine the motivation for ad blocking. LEAN is an acronym for lightweight, encrypted, AdChoices-supported and non-invasive. Each of the specs will be based on HTML5 technology.

"Our brands and agency that are deploying the market need an easy way to deploy across multiple screens," Ms. Gombert added. "The flexible units are much more easily customizable to cross-screen. That is what they were made for."

About 51 million people run ad blockers on desktop computers, according to a study released Monday by Adobe and PageFair. That number is far smaller on mobile. Ms. Gombart said the push toward the new ad units was not meant to thwart ad blocking adoption on mobile.

"At the end of the day we're advertising," Ms. Gombert said. "To be clear this is not an anti-ad blocking initiative. It is a creative initiative to tell a better story and provide a better experience across screen. That is the spirit of this."