Although there is a slight chance that the expert will disagree with me, I would say: the building envelope in the development plan is not a guarantee, i.e., the development plan issuer has not previously checked all land registry files, but with the parcel-specific building envelope (where available) only makes the statement that, according to the will of the development plan issuer, the possible location of buildings should not be restricted solely by the setback according to the respective state building code, but rather specified more precisely. Building envelopes for individual plots are generally not the norm; they are mostly found only where infill plots in an area with an old development plan or previously §34 are being replanned (as imagined lines around existing building outlines, and then translated from the actual building envelopes to the infill plots). As another case, I only know this insofar as it is to be ensured that neighboring buildings allow more "side" lighting through shifts in building lines. Apart from these two special cases, I typically see building envelopes in newly created building areas as spanning across parcels. Therefore, I consider a derivation of a negation of setback area assumptions from the building envelope drawing to be far-fetched.