The guidelines, set by the Interactive Advertising Bureau's Rich Media Task Force on Monday, are meant to help encourage and streamline the creation of "rich media" units -- advertisements that typically include animation, audio or video. Rich media ads have become increasingly common. CNET Networks, publisher of News.com and ZDNet UK, introduced the ad units earlier this year. Other online media outlets, such as Salon.com and the New York Times, quickly followed suit. The ad units allow consumers to interact with a marketing message, scrolling through information without leaving the page. In an extreme example, a recent Oracle ad on the New York Times Web site showcased a fighter plane that zoomed across the page and landed onto a ruler-sized ad known as a skyscraper. Such intrusive advertising has drawn heated criticism from Web surfers, who are accustomed to standard banners and smaller ad buttons. Yet amid a slack advertising market, Web publishers have become increasingly flexible and inventive to attract traditional advertisers to their sites. Earlier this year the IAB introduced new standards for larger ad units, including pop-ups, skyscrapers and interactive marketing units. The rich media guidelines relate to several such established ad sizes, including the standard banner ad, newly sanctioned IMUs, skyscrapers and pop-up ads. Last month, the IAB, Microsoft and DoubleClick issued new research promoting the larger units as more effective at leaving an impression with consumers. As online advertisements grow bigger and more prominent, the more useful they become in conveying a marketing message, the studies showed. Monday's guidelines "are meant to assist publishers, advertisers and their agencies in creating meaningful and effective interactive advertising," IAB chief executive Robin Webster said in a statement. "Recently released research findings...reinforce earlier research...that size and interactivity are both important. Previous IAB voluntary guidelines have focused on size. These new rich media guidelines encourage adoption of interactivity within the ad units," Webster said. The guidelines list technical requirements for several IAB-approved advertising units. For example, guidelines for a standard banner including rich media technologies such as HTML, Flash or Java require that the file size be limited to 15K initially, then allow up to 85K after a visitor interacts with the banner. The voluntary standards also set out that a banner only play audio or video after a visitor clicks on the ad. It must also contain a "stop" button. The IAB also set testing guidelines for designers to gauge the stability of an ad in various browsers to avoid errors or page delays. Companies that helped define the IAB's rich media standards include Ask Jeeves, CNN Interactive, DoubleClick, Excite@Home, MSN, Yahoo and CNET Networks. The group also consulted advertising agencies and ad technology companies before finalising the guidelines. The group plans to meet in the next 6 to 12 months to review the standards. See the Internet News Section for full coverage. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the Telecoms forum. Let the editors know what you think in the Mailroom. And read other letters.