/usr/share/desktop-directories/ is in ubuntustudio-menu 0.25.
This file is owned by root:root, with mode 0o755.
..
/usr/share/desktop-directories/ubuntustudio-audio-utiliy.directory
/usr/share/desktop-directories/ubuntustudio-audioproduction.directory
/usr/share/desktop-directories/ubuntustudio-effects.directory
/usr/share/desktop-directories/ubuntustudio-graphics.directory
/usr/share/desktop-directories/ubuntustudio-info.directory
/usr/share/desktop-directories/ubuntustudio-mediaplayback.directory
/usr/share/desktop-directories/ubuntustudio-midi.directory
/usr/share/desktop-directories/ubuntustudio-mixers.directory
/usr/share/desktop-directories/ubuntustudio-noshow.directory
/usr/share/desktop-directories/ubuntustudio-photography.directory
/usr/share/desktop-directories/ubuntustudio-synths.directory
/usr/share/desktop-directories/ubuntustudio-video-audio-tools.directory
/usr/share/desktop-directories/ubuntustudio-videoproduction.directory