XkbGetKeyExplicitComponents(3) on Linux

The text 590190d2ced6, as Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie), Debian 7 (Wheezy) shipped it.

Obtain the explicit components (the explicit array) for a subset of the keys in a keyboard description