XmStringTableToXmString(3) on Linux
The text c43e1de30f7e, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A convenience function that converts a compound string table to a single compound string "XmStringTableToXmString"