syntax-highlight .lang file targeting iCalendar files .ics to be used by GtkSourceView (gnome-text-editor / gedit)
with this you'll get a nice syntax coloring of your .ics calendar files at the text editor
the file should be placed at /usr/share/gtksourceview-5/languages-specs
https://github.com/GNOME/gtksourceview
https://developer-old.gnome.org/gtksourceview/stable/lang-tutorial.html
https://gitlab.gnome.org/GNOME/gnome-text-editor
https://github.com/GNOME/gedit
https://github.com/jonocodes/GeditSchemer