 Apple provides a large collection of system-declared Uniform Type Identifiers.Third-party applications can add UTIs to the database maintained by macOS by "exporting" UTIs declared within the application package.Because new UTIs can be declared to "conform to" existing system UTIs, and declarations can associate the new UTIs with file extensions, an exported declaration alone can provide the operating system with enough information to enable new functions, such as enabling Quick Look for new file types.