The Apple Developer Connection has published “Simplifying Data Handling with Uniform Type Identifiers.” Apple notes “Uniform Type Identifiers (UTIs) are strings that specify abstract types in Mac OS X. For developers, UTIs can help you take advantage of Launch Services, Navigation Services, Pasteboard Manager and Translation Services, and work more easily with Spotlight and Automator. Read this article if your Mac OS X application creates or manipulates data that may be exchanged with other applications or services.”