XmFontListNextEntry(3) on Linux
The text 4ad9613b6ae7, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A font list function that returns the next entry in a font list "XmFontListNextEntry" "font list functions" "XmFontListNextEntry"