on a block of downtown san francisco, there are two block-long lines labelled ‘address interpolation’. there aren’t many nodes along this block, but the ones that exist mostly have explicit addresses assigned.
these were created 14 years ago (potlatch 0.10f). what do they do, are they valuable to renderers or to the map itself?
It’s documented in the wiki: https://wiki.openstreetmap.org/wiki/Addresses#Interpolation
It was very useful in the early days, when no housenumbers were mapped, to fill the map quickly. If all numbers mapped since, you can delete this line.
Search and navigation software supports these elements. I just checked, osmand interpolates the location of a number if you search for it. Nominatim and OrganicMaps both just find this line if you search for an intermediate number.