SBC Intellectual Property owns two U.S. patents on a Web site navigation tool called a "structured document browser" and it is asking MuseumTour.com and other sites to pony up licensing fees.The structured document browser's definition sounds like the technique of using frames to link to other documents on a Web site, which would be used by hundreds of thousands, if not millions, of sites. SBC Intellectual Property President Harlie Frost said the patent claims are "related to frames" before referring more questions to SBC's public relations representatives."If you find something interesting in this, that'll be curious to me," Frost said of the patent claims.Several Internet activists, including members of the free software movement, have for years blamed the U.S. Patent and Trademark Office for granting patents on technologies that were already widely used. The most publicized case was in September 1999, when Amazon.com was granted a patent for its one-click shopping service. Amazon.com CEO Jeff Bezos later called for patent reform.According to U.S. patent No. 6,442,574, dated Aug. 27, 2002, a structured document browser "includes a constant user interface for displaying and viewing sections of a document that is organized according to a pre-defined structure." The documents are tagged with embedded codes, and the tags are "mapped to correspond to a set of icons. When the icon is selected while browsing a document, the browser will display the section of the structure corresponding to the icon selected, while preserving the constant user interface."A similar patent, No. 5,933,841, was filed by Ameritech in May 1996, and was granted Aug. 3, 1999. SBC Intellectual Property, a division of telecommunications company SBC, now owns that earlier patent.SBC Intellectual Property released a statement in response to questions about the patents, saying actively protecting patents is a common practice among patent-holders.SBC Intellectual Property is working with several commercial Web site owners on the structured document browser patents, the statement continued. "SBC Intellectual Property is committed to working with these and other entities to establish patent licensing terms that are reasonable and fair for all parties."An SBC PR representative said he couldn't comment further.SBC's letter, outlines licensing fees for sites using SBC's patents. The fees range from $527 for an annual royalty for a company with a revenue of $100,000 a year, to $5 million for a fully prepaid license for a company with a revenue of $10 billion a year.MuseumTour.com, an educational products catalog site owned by Informal Education Products, received the licensing letter from SBC Intellectual Property last Thursday, according to Marilynne Eichinger, president of MuseumTour.com.MuseumTour.com's lawyers are reviewing the licensing claim, she added, and she's hoping to hear from owners of other sites who have received similar letters. "I find it difficult to understand their exact claim which is why our lawyers are reviewing the patent," she said. "Once they tell me their opinion I will decide what to do next."The SBC patent claim began to make the Web log rounds this week. The Larkware.com site, operated by programmer Mike Gunderloy, offered its definition of a structured document browser:"Just in case you're not fully up on reading patent language, that means that if your Web site uses frames, and there's a navigation frame on one side, with links that load content into the main frame - you're violating their silly patent, and they can come after you for licensing fees. This is so staggeringly stupid that it's difficult to know where to start, other than with the obvious observation that the (U.S. Patent Office) has no business granting this sort of junk patent."But Chicago patent defense lawyer Peter Trzyna defended SBC's actions in an interview, saying SBC is "not the kind of company that would spend the tens of thousands of dollars it'd take to get a frivolous patent."Critics of the patents generally aren't patent-holders, and haven't had to "fight through tough examiners," added Trzyna, who has both worked for SBC and against SBC in the past.Asked if this patent claim could affect thousands of Web sites, Trzyna answered: "It could very well. People make inventions that the world later comes to use."