With the file abc.lang you add syntax highlighting support for
ABC Music Notation files to GTKSourceView in common or to GEdit in special.
Simply copy abc.lang to ~/.local/share/gtksourceview-3.0/language-specs -
you can also use install.sh for this purpose.
To make the syntax highlighting avaialble to all users, copy the file
to /usr/share/gtksourceview-3.0/language-specs.
See LICENSE.md
Details about GTKSourceView syntax highlighting: https://developer.gnome.org/gtksourceview/stable/lang-tutorial.html
Details about the ABC Music Notation format: http://abcnotation.com/wiki/abc:standard:v2.1