XmConvertUnits(3) on Linux
The text 1d79d415cb8f, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A function that converts a value in one unit type to another unit type "XmConvertUnits"