Gartner is almost as suspicious of Microsoft's week-old interoperability promises as European Commission antitrust chief Neelie Kroes. It's warning open source developers to beware the patent trap. 'Do not use Microsoft's documentation,' it says, 'unless you have rigorous processes to keep track of applicable patents. Keep work that depends on these patents separate from other OSS work to avoid exposing downstream distributors and user to litigation risk.'