used Infoseek portal has decided to no longer accept advertising from adult Web sites. In general, adult ads pop up after a search engine user asks for a list of sites which emphasize sexual content. The user puts in words like "sex" or "XXX" or "hot teens" and the ad appears at the top of a list of sites. Advertisers believe, with good reason, that the ad gives them an edge in drawing Web browsers looking for sexually explicit material. \n Up until now, major portals have accepted adult ads. Infoseek may be the first to decline the lucrative revenue from adult advertising. \n The change of heart, explained Infoseek president Harry Motro, is that his company believes it must act like a global media firm. In making the move, the company follows the policies of such giants as America Online and Microsoft, which operates MSN.com, huge Internet providers which refuse adult business. \n It's not exactly clear how much revenue Infoseek will lose as a result of its decision. Industry analysts estimated a couple of years ago that about 20 percent of search engine ad money comes from adult sites. Since then, however, other advertisers have entered cyberspace and adult ads may have dropped to less than 10 percent of total revenue. \n By declining porn site messages, Infoseek puts pressure on other portals to do the same. Special interest groups may use Infoseek's example to persuade other search engines such as Excite, Yahoo and Lycos to adopt a no-porn ad policy. \n Infoseek's new ownership may have played a part in the change of policy. Although Disney units turn out movies with sex and violence and Disney-owned ABC is the home of "N.Y.P.D. Blue," the company has generally emphasized its dedication to wholesome, family-oriented recreation and programming.