I will answer in english just in case anybody is interested.
In Gamestudio you can define so called "regions" - a bbox with a name that can be used to cull out explicit things from your scene.
From the manual:
The A8 engine supports special portals that are controlled by script. For this, rectangular portal regions can be placed in WED. Such a region, when activated with a script command, culls all its objects from the PVS. This can be used for disabling the rendering of objects inside a room or building as long as the camera is outside or the doors are closed.
In WED it is possible to set such a (static) region in your level.
You can use the functions region_set, _check, _get, _find to deal with it, but you can also use _create to dynamically define them.
It integrates both with Gamestudio's ABT and BSP tree rendering algorithms.
GED : I wouldn't care about that - I always use WED - it is battle-proven, simple and powerful at the same time.
Besides, GED emerged from a hobbyist project, was pushed by a single person to become a product and failed big time. OpGroup always promised a WED 2 - but I wouldn't care about that either as long as it isn't released.