It is essentially a giant, U-shaped magnetic coil that causes interference in the atmosphere that prevents enemy units and command interfaces from mapping or exploring a segment of the battlefield in its close proximity. A mobile version of the generator, the Mobile Gap Generator, was also produced during the Second World War.
Despite the Gap Generator's ability of creating vast patches of shroud, any Allied unit within the shroud can still be targeted by enemy units, even airstrikes.
The Gap Generator creates a persistent shroud in a radius around the structure. This shroud is lifted by units traveling through as normal, but it returns as the unit moves away. The shroud will regenerate in this manner so long as the structure is standing and there is adequate power available.