XmAddWMProtocols(3) on Linux
The text e58cb7fb1881, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A VendorShell convenience interface that adds the protocols to the protocol manager and allocates the internal tables "XmAddWMProtocol\%s" "VendorShell functions" "XmAddWMProtocol\%s" "protocols"