definition
strict definition
street tier
The tier holding streets, the reference an address is built on rather than an area of land.
The street tier holds the roads an address refers to. It sits apart from the area tiers: a street is a line rather than a surface, and an address is a point on it.
The tier exists so that an address can name something recorded rather than a free text, and so that everything on one street can be found together.
What kind of road it is, whether a highway, a boulevard or a lane, is the region type.