"We have people who are monitoring Microsoft and we will continue to block their program," said Tricia Primrose, an AOL spokeswoman in the U.S. Meanwhile, software pioneer John McAfee, who heads a small instant messaging company that competes with AOL, said he believes AOL will summon the resources to enforce its ban, leaving Microsoft no recourse but to go to court. "Can AOL continue to shift its architecture to prevent Microsoft, Yahoo and the rest from using its database (of instant messaging users)? My guess is 'yes' -- if you're committed to something like that in the software industry you can make it happen." This, on the same day British legal experts predicted the ISP would seek a restraining order against Microsoft. The battle between AOL and Microsoft began last week when Microsoft and other companies launched instant messaging clients that allowed users to access AOL's popular service. AOL retaliated over the weekend, changing the protocols to block the programs from Microsoft and Yahoo! Inc. Brian Park, senior producer at Yahoo, said his company used the Unix protocols published on AOL's site to develop their client. There are several clients for AIM available in Linux. "The AIM site had a link saying 'Get information and downloads for Windows, Mac and Unix.' If you clicked the link for Unix, all the protocols were available," he said. "It never said [the protocols] were only for Unix clients. It was very open, so we used those open protocols to build our product." But the links to the protocols disappeared from AOL's site a week or so before the launch, Park said. By Friday, AOL had changed the protocols, and neither the Yahoo nor the Microsoft clients were able to interconnect with AIM. "It shows AOL's unwillingness to work with the developer community to broaden their products and allow them to add on to them," Park said. Primrose did not comment on the status of other AIM clients and AOL UK refused to do so. Park said that unlike Microsoft, his company would not try to develop a work-around to the AOL blocks. Microsoft has been working persistently to continue its link to the AOL service, and says it has received many requests from its customers for interoperability. "It's obviously something consumers are demanding. That's why Microsoft and a number of others are supporting [proposed standards]," said Microsoft spokesman Jason Standifer. Primrose said AOL sent Microsoft a letter Friday requesting that the two companies "figure out a solution." But she made it clear how AOL sees its role in any discussions of a common standard. "We think we're in a position to help lead the way. We think we can have important input," she said. "But I wouldn't say carte blanche we would support any standards that would be proposed." What is your view? Should AOL allow other services to communicate with its users with AIM Tell the Mailroom -- to be published Friday.