This can be a unit designator, such as apartment number, suite number, or floor. There may be several unit designators in an address (e.g., "3rd floor, Appt. 342"). This can also be a designator pointing away from the location, rather than specifying a smaller location within some larger one (e.g., Dutch "t.o." means "opposite to" for house boats located across the street facing houses).
Project FHIR API
This is the location where you can find your resource using a FHIR client.
Simplifier FHIR API
The global endpoint is where users can search for all resources in Simplifier. Resources have a globally unique guid Id here.