Ah thank you - I get it now.

We wouldn't have that problem in France where the cities are clearly separated. The concept of "city" (commune) is the basis for the topography classification of the country since 1789.

So when I input an address, a suggestion system will give me several choices with several distinct cities and zips. If I input a zip code, I can get several choices of "places" under one zip.

A situation where your address is in the neighbour city should not happen (I put "should" because this is France :))