Reference

XSetIconName(3x) on Linux

The text 1871a4ed8417, as Debian 2.2 (Potato), Debian 2.1 (Slink), Debian 2.0 (Hamm), Debian 1.3 (Bo) shipped it.

set or read a window's WM_ICON_NAME property

XSetIconName(3x) on Linux now