4Sight was the default window manager for Silicon Graphics' UNIX variant IRIX from version 3.0 to 3.3.3L. 4Sight ran under a hybrid window system known as xSGINeWS (generally called XNeWS): a combination of MIT's X11 and Sun Microsystems' NeWS. The introduction of the IRIS Indigo featuring IRIX 4 in 1991 marked an end to SGI's use of XNeWS under IRIX. All IRIX releases from 4.0 to 6.5.30 utilized X11 (Xsgi) and SGI's modified Motif window manager 4Dwm.