XmActivateProtocol(3) on Linux
The text b138d14cf360, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A VendorShell function that activates a protocol "XmActivateProtocol" "VendorShell functions" "XmActivateProtocol" "protocols"