XmDataFieldSetInsertionPosition(3) on Linux
The text ec13912dd30e, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A DataField function that sets the position of the insertion cursor "XmDataFieldSetInsertion\%Position" "DataField functions" "XmDataFieldSetInsertion\%Position"