Key:addr:flats
|  addr:flats | 
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| Description | 
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| The range of unit numbers within a larger building or complex. For example the range of flats behind the entrance door of a building.   | 
| Rendering in OSM Carto | 
|   | 
| Group: addresses | 
| Used on these elements | 
| Useful combination | 
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| See also | 
| Status: de facto | 
| Tools for this tag | 
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Use addr:flats=* for marking the range of numbers of flats in a building or behind a door, for example, addr:flats=97-117. If there is a gap in numeration, mark numbers and intervals with semicolon: addr:flats=3-7;10;14;16-18.
Is some regions, if there is only one flat, the tag addr:unit=* is normally used instead.
A leading semicolon can be used when a flat number is implicit. For example, a house at '10 Some Street' converted into 3 flats with postal addresses of '10 Some Street', 'Flat 1, 10 Some Street' and 'Flat 2, 10 Some Street' can be tagged addr:flats=;1-2 and addr:housenumber=10.
How to map
Where there are multiple entrances to the building and each entrance leads to a different set of flats, then tag the respective addr:flats=* on each entrance.
Where the building only has one entrance or there are multiple entrances but each entrance is not marked for a specific set of flats, then you can either tag addr:flats=* on the main entrance=* node, or on the building=* way.
You should only place addr:flats=* on multiple entrance=* nodes where the value of addr:flats=* is not the same on each entrance=*.
Rendering
Example of addr:flats rendered on osm.org:

Similar tags
addr:flat=* - is used 103 times as of 2022-06-06, and is not documented.
This seems to be mostly used on businesses, and could perhaps be replaced with addr:flats=* or addr:unit=*.
See also
- building:flats=*- to specify the total quantity of flats (apartments/units) in a building.
- addr:unit=*- for the address of a single unit, including flats, offices etc.
- ref=*- for reference code of entrance (present in some buildings where there are multiple staircases - staircase coded as 1, 2, 3... or A, B, C... or I, II, III... are common)







