document display addresses and unit type

1 files changed, 14 insertions, 0 deletions

diff --git a/README.md b/README.md
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+++ b/README.md
@@ -89,3 +89,17 @@ For these reasons this building / property name is not included, however it coul
 Source data sometimes includes a complex name, for example _CHADSTONE SHOPPING CENTRE_ or _MELBOURNE UNIVERSITY_. These attributes are not used as these names should appear on the actual feature like `shop=mall` or `amenity=university`.
 
 They might be of interest for mappers as an additional data source, externally to this import.
+
+### Display Address
+Source data has a display address which can differ from the official address. For example if a building is `1-3` but is signed as simply `1`. Currently we ignore the display address, and while this can be seen as more correct based on the "official" address, does it go against the OSM principle of mapping what's on the ground?
+
+### Unit Type
+Unit values have a designator set eg "UNIT 1", "SHOP 1", "SUITE 1", etc.
+
+The `addr:unit` tag expects the value, "1" from the given examples, not a full string like "UNIT 1", so we don't include this designator in the `addr:unit` value.
+
+One potential solution is to encode this in the `addr:` key like `addr:unit`, `addr:shop`, `addr:suite`, however these can still all be considered "units" so this is not preferred.
+
+Another solution is use a new tag like `addr:unit:prefix=Unit`, although there is no existing usage of this tagging scheme ([taginfo](https://taginfo.openstreetmap.org/search?q=addr%3Aunit#keys)).
+
+Alternativly this information could be omitted.