EN:Le Schéma de Charlieu : une proposition autour des adresses

This is an English translation of the original French proposal.

This page aims to formalize a proposal intended to improve address mapping in France (and perhaps elsewhere) within OSM.

It presents:

A model for address tags using two key prefixes: addr: (for addresses themselves) and contact: (for addresses associated with points of interest (POIs)).
A discussion of their placement.
A mapping guide incorporating these principles.

More details at taginfo

Definitions and Discussion

The Composition of an Address

An address, particularly in France, is generally characterized by four levels of definition, from the most precise to the broadest:

The house number, which gives a position relative to the street to which it belongs. Two systems coexist: the even/odd numbering system (historical, commonly found in cities) and metric numbering (the number corresponds to the distance in meters from the beginning of the street, mostly found in rural areas). Ideally, a number should be unique and refer to a single location.
The street and its name, for example: Avenue des Champs-Élysées. Geometrically, streets can be represented as lines.
The postal code: a five-digit code (e.g., 45100), which is a technical area created by La Poste. Its scale ranges from inter-municipal to sub-municipal (neighborhood) level.
The municipality, according to official administrative boundaries.

In rural areas, addresses are also sometimes defined by localities (lieux-dits), whose boundaries are generally vague. A locality may refer to a single house, a hamlet, or sometimes an entire neighborhood. Note that many localities are uninhabited.

Addressing is a municipal responsibility in France. Municipalities are required to name and define streets and assign numbers to them. Therefore, municipalities determine when assigning a unique number is necessary. Some cases are obvious, such as suburban housing developments where a parcel or house can easily be associated with a number. Others are less clear, such as apartment buildings, which may have either a single number or several numbers assigned to individual entrances.

What Does an Address Refer To? The Problem of 1 Address = 1 Place

There is no consensus regarding what exactly an address represents in OSM (or elsewhere) and what it should be associated with. It may refer to physical elements (an entrance, a gate, a house, a building, a mailbox) or functional entities (a parcel, a business, a household, a residence, a factory, etc.).

Therefore, there is no universal schema such as 1 address = 1 household, 1 address = 1 residence, or 1 address = 1 business. Depending on the service using the address, it may be associated with different objects. For example, tax authorities use addresses to associate tax households, while a service such as La Poste associates addresses with delivery locations such as mailboxes or front doors.

Towards a Definition of the Address as a Distinct Object

Faced with this identification problem, we can nevertheless attempt a broader definition of an address, at least for OSM, if we consider that an address should primarily serve navigation:

A geolocated number along a street, located at the interface (generally an entrance) between a publicly accessible road and one or more unspecified places associated with that address (or multiple addresses).

With this logic, the goal is no longer necessarily to associate an address with a single precise location. Instead, an address is simply mapped wherever it exists, in relation to the street to which it belongs.

Principles of the Charlieu Schema

According to this proposal, addresses are mapped using two complementary approaches:

The address as a unique geolocated object, independent of the place(s) to which it may be associated. Tagged with the prefix addr:, ideally represented by a standalone node at an entrance.
The address as an attribute of a POI, tagged with the prefix contact:.

This approach is inspired in part by an unadopted 2013 proposal known as the Bremen Schema, which sought to avoid duplicate addr: street-number tags when the same address was associated with multiple POIs.

The name "Charlieu Schema" comes from the municipality of Charlieu (location on OSM), which has already been fully mapped according to these principles and can serve as a model (see Overpass Turbo query).

Advantages and Intended Goals

To provide more relevant and standardized address data for navigation (using addr:): for a given address, it should be possible to find a single addr:housenumber leading to the most appropriate interface (typically an entrance) between the street and the associated place(s)...
...while preserving the possibility of associating addresses with places through contact: tags on POIs.
To avoid duplicate addr:housenumber values.
The use of the contact: prefix for POI addresses is consistent with the existing tagging scheme for other contact information such as telephone numbers, websites, and email addresses, although this schema remains subject to debate (data fragmentation compared with older tags such as phone or email).
Reuse of address data by applications is not fundamentally altered. POI addresses stored using contact: should simply be displayed alongside other contact information such as telephone numbers, email addresses, and websites. House numbers stored in contact: should not necessarily be displayed on the map itself but should still allow users to find the corresponding POI through search.
Some applications already display POI addresses tagged with contact:, including CoMaps and Cartes, while OsmAnd has considered supporting it (Github discussion). OpenStreetBrowser displays POI addresses when stored using contact:.

Disadvantages

Documentation conflict regarding the use of the contact: prefix: the English OSM wiki states that it should be used for POI addresses that differ from their physical address. However, actual usage corresponds to the Charlieu Schema in 99.1% of cases (verified on 2025-07-30), with only 651 of 72,218 objects having a contact:housenumber different from addr:housenumber. Should the documentation be revised to reflect the Charlieu Schema, which currently matches the most widespread practice, and should another prefix be introduced for cases where the postal address differs from the physical address, such as contact:postal:?
Data fragmentation if this model is only applied locally. Currently, the Karlsruhe Schema is widely used throughout OSM worldwide.
Many navigation applications based on OSM still rely on addr: tags to display POI addresses. If an address is only stored using contact:, it may be ignored.

How to Map

Using `addr:` for Addresses Themselves and `contact:` for POI Addresses

Addresses themselves should be mapped using tags with the addr: prefix in OSM.

See FR:Key:addr for more information (particularly regarding addresses in multi-unit residential buildings).

Each address should be unique and represented by a single geometry.

	Key	Value (example)	Comment
House number	`addr:housenumber`	`85`	Required
Street name	`addr:street`	`Avenue Lucie Aubrac`	Required (see also associatedStreet relation)
Local place name or name of business park	`addr:place`	`Les Bajards`	Optional. Localities can be a useful complement to an address. In rural areas, they may even be the only information below the municipality level. The same value may apply to multiple nodes. Similarly, POIs in industrial zones may not have street numbers; the zone name can be used here.
Postal code	`addr:postcode`	`80000`	Optional. Redundant, as most applications can derive it spatially. However, it may be useful when a POI lies across two municipalities.
Municipality	`addr:city`	`Amiens`	Optional. Redundant, as most applications can derive it spatially. However, it may be useful when a POI lies across municipal boundaries.

Important: Addresses of Points of Interest (POIs)

POI addresses (for example schools, shops, or town halls) are tagged using the contact: prefix. These tags are added directly to the POI, regardless of its geometry .

A POI should not contain addr: tags unless its geometry directly corresponds to the meaning of the address (1 place = 1 address).

Multiple POIs may share the same address.

	Key	Value (example)	Comment
House number	`contact:housenumber`	`25`	Required
Street name	`contact:street`	`Rue Sister Rosetta Tharpe`	Required
Local place name or name of business park	`contact:place`	`Les Béluses`	Optional. Localities can be a useful complement to an address. In rural areas, they may be the only information below municipal level. The same value may apply to multiple POIs. Similarly, POIs in industrial areas may not have numbering; the zone name may be used.
Postal code	`contact:postcode`	`80000`	Optional. Redundant, as most applications can derive it spatially. However, it may be useful when a POI spans multiple municipalities.
Municipality	`contact:city`	`Amiens`	Optional. Redundant, as most applications can derive it spatially. However, it may be useful when a POI spans multiple municipalities.

How to Map and Place the Address

Using a node (recommended).
On the building outline if it represents a single address.

In general, it is recommended to use a node because it covers most real-world cases. It avoids the difficulty of deciding what exactly the address refers to and is usually sufficiently precise.

The node should preferably be placed at the interface between the road and the property or building, near an entrance (whether it opens onto a garden or directly into a building). However, when in doubt, always choose the placement that makes the address least ambiguous.

	Practical guide for placing `addr:` nodes (non-exhaustive)
Case		Recommendations
Description	Illustration	Comment	Illustration
Detached house with garden (suburban development)		The node is placed at the entrance (gate) of the property, at the interface between the road and the parcel.
House whose entrance opens directly onto the street (townhouse)		Place the node on the building façade facing the street, ideally at the entrance door.
Multi-storey residential building with entrances directly accessible from the street		If several entrances exist, place nodes for each numbered entrance on the façade. Add `addr:housename` if the building has a name.
Mixed-use building with shops on the ground floor and apartments above		The `addr:` node is placed on the building façade facing the street, and `contact:` tags are used on the POIs of the shops.
Isolated rural dwelling with a long private access road		If the access road is private, place the node at its end, at the interface with the public road.
	Two houses on the same property with different addresses but a shared gate		Place nodes directly on each house façade, ideally near their entrances, to avoid ambiguity.
	Multiple rural dwellings at the end of a long shared access road (no internal fencing)		Place nodes directly on the façades of the houses if their numbers are known.
	A shopping arcade with its own parking and entrance but a single address		The node can be placed at the entrance to the parking area, at the interface with the public road.