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?
I don't know how it renders, but the idea was you could mark the address at the beginning of the block and the address at the end of the block, and then address finders would try to guess the intermediate addresses if anybody asked for them.
I think they've fallen out of favor and now people just add addresses to every building. Maybe.