XmClipboardCopy(3) on Linux
The text 529a04047cac, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A clipboard function that copies a data item to temporary storage for later copying to clipboard "XmClipboardCopy" "clipboard functions" "XmClipboardCopy"