XmRepTypeValidValue(3) on Linux
The text dfe970694e12, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A representation type manager function that tests the validity of a numerical value of a representation type resource "XmRepTypeValidValue" "representation type manager functions" "XmRepTypeValidValue"