A commercial software team contributed to an open source implementation of the Windows API on X-Windows and Unix. Wine is an open source implementation of the Windows API, a compatibility layer that lets native windows programs run on X-Windows and Unix. With our contribution filling in some gaps, our client planned to include Wine with a slightly modified product. Expecting chaos in the organization and code, the team instead found a structured community with procedures all its own. The version control tool on the Wine team is CVS (concurrent version system), an open source, network-transparent version control system. Patches on Wine are relatively small, which makes them easier to review and less risky to add to the source tree.