Rime is a framework for input methods, and '鼠鬚管' (Squirrel) is its application on macOS. The system configuration directory is "/Library/Input Methods/Squirrel.app/Contents/SharedSupport/", while the user configuration directory is ~/Library/Rime/. The main files in the user configuration directory are installion.yaml, user.yaml, and the build directory, which contains compiled files generated after '重新部署' (redeploy). The xxx.userdb directory contains user dictionaries for each input scheme, and the sync directory is used for synchronizing user data.