The direct neighbours of the owner or renting party of real estate (a room unit) X are the owners and renting parties of all room units that geographically are directly adjoint to X.
The nearby neigbours of X are all direct and indirect neigbours that are not more than 200 metres (parameter) away (the smallest distance of the 2 room unit's borders).
The complete set of neighbours of X is all direct and indirect neigbours that
(a) have a direct view to at least 1% (parameter) of the room unit
(b) are not more than 2'000 metres (parameter) away (the smallest distance of the 2 room unit's borders)
(c) are nearby neighbours