/usr/share/xsessions/Fvwm1.desktop is in fvwm1 1.24r-56.
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 | [Desktop Entry]
Encoding=UTF-8
Name=Fvwm1
Comment=Fvwm1
Exec=fvwm1
Terminal=False
TryExec=fvwm1
Type=Application
[Window Manager]
SessionManaged=true
|