The browser has two kinds of J3D structures: permanent structures which
are changed the current scene and reset for each URL, and a scene
branchgraph which holds the J3D tree parsed from the current VRML url.
Evagation \Ev`a*ga*tion\, n A wandering about, excursion, a roving.
(Source: Webster's Revised Unbriged Dictionary (1913))
This is the event controller for the VRML runtime.