/usr/share/themes/Radiance/index.theme is in light-themes 0.1.9.1-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 | [Desktop Entry]
Type=X-GNOME-Metatheme
Name=Radiance
Comment=Ubuntu Radiance theme
Encoding=UTF-8
[X-GNOME-Metatheme]
GtkTheme=Radiance
MetacityTheme=Radiance
IconTheme=ubuntu-mono-light
CursorTheme=DMZ-White
ButtonLayout=close,minimize,maximize:
|