After a year of legal fits and starts -- and repeated attempts to clean up some copyright violations on its own -- Napster's antipiracy efforts are finally official. At the end of the day Monday, the company sent a federal court documentation outlining how it is officially complying with a preliminary injunction issued early last week, which requires the company to block numerous copyrighted works from being traded through its service. Although the company has had its screens up for a week -- and has been fine-tuning them as people find ways to slip their songs through the mesh -- this is the first time Napster has officially had to show that its internal efforts are in line with the court's order. "I think Napster is complying with the injunction both in the letter and in the spirit," said Napster chief executive Hank Barry. It's clear, however, that the injunction is a work in progress on both sides, with Napster and the record companies struggling to force their own technologies and databases into the terms laid out by the court. Barry conceded that variants of blocked songs are still slipping through, noting that the company has people manually entering common misspellings of file names into the screens' databases. But the record companies, too, are apparently having some difficulty complying with the exact terms of the injunction. Of 135,000 song titles submitted to Napster by the record industry last Friday, more than a third did not include the file name that US district judge Marilyn Hall Patel said was necessary to trigger a block. All of these 46,000 songs came from Sony Music Group, Barry said. Record industry representatives could not immediately be reached for comment. The two-thirds of the songs that did comply with all the terms of the injunction will be blocked by Wednesday night, Barry said. Up to this point, outside observers have said that Napster's filters have had almost no effect on the service's traffic. Research company Webnoize, which monitors traffic flowing through Napster's service, said that traffic last week actually jumped from the week before by more than 3 percent, with an average of 1.66 million people on the system at any given time. The filters "don't seem to have deterred anyone from using Napster", said Webnoize analyst Matt Bailey. He added, however, that he expects use to drop off sharply when the second version of the filters containing the record industry's long list of songs actually goes into place. Meanwhile, Napster appeared to be gaining ground on the simplest attempts to evade filters. Common misspellings, which had made it easy to find even blocked songs last week, had for the most part disappeared by Monday. Pig Latin versions of song titles, artists and file names, a filter-evasion measure propagated by rival company Aimster and several other sites independently, had also been blocked in many cases. Napster has contacted some of the people spreading these anti-filter technologies and asked them to stop. Aimster confirmed late Monday that it was taking its Pig Latin system down at Napster's request and had stopped development of a more powerful program for evading the filters that had been dubbed "Scorpion". Barry said Napster is also developing a software program that will search out variants of song names that are slipping through the filters -- it has contacted outside companies including Gracenote and NetPD for help. NetPD is the same company that originally helped Metallica and Dr Dre find infringing files on Napster's system last summer. Take me to the MP3 Special Have your say instantly, and see what others have said. Click on the TalkBack button and go to the Napster Debate. Let the editors know what you think in the Mailroom. And read what others have said.