Key:ref

"ref" stands for "reference" and is used for reference numbers or codes. Common for roads, highway exits, routes, entrances to big buildings etc. It is also used for shops and amenities that are numbered officially as part of a retail brand or network respectively.

This key and variations are frequently used to avoid the use of relations.

Key variations

• ref=*
• int_ref=* - international reference numbers or codes
• nat_ref=* - national reference numbers or codes
• reg_ref=* - regional reference numbers or codes
• loc_ref=* - local reference numbers or codes
• old_ref=* - old or former reference numbers or codes (usually replaced with another)
• unsigned_ref=* - reference number of code that is generally not signed on the route
• prow_ref=* - Public right of way reference (England and Wales only)
• alt_ref=* - alternative reference number or codes

Core values

None

User defined values

Any valid syntax value

Examples on relations

place=* nodes and boundary=administrative relations for states and provinces are often tagged with a postal abbreviation in ref. For example:

• Administrative boundary relation for the U.S. state of California: ref=CA (165475 165475)

On route=road relations, the ref is a bare "route number",^[59] relying on network=* to convey information about the road network:

• Interstate 35W in the United States, conventionally abbreviated I-35W: network=US:I ref=35W on the relation, ref=I 35W on the member ways
• Japan National Route 282, conventionally abbreviated 国道282号: network=JP:national ref=282 on the relation, ref=282 on the member ways

Similarly, on cycle and walking routes, the ref is a bare number and cycle_network=* indicates the route network:

• United States Bicycle Route 76: cycle_network=US:US ref=76

Bus routes use ref to label the bus route. For example:

• Bus route 23: ref=23 (type=route, route=bus, name=Shanklin>Newchurch>Newport - currently 312207 312207)

Examples on ways

• ref=A 1 Default reference (German and French references with a space; e.g. A 1)
• int_ref=E 15 Internationally referenced as
• nat_ref=A 1 Nationally referenced as (German and French references with a space; e.g., A 1)
• reg_ref=A 1 Regionally referenced as (German and French references with a space; e.g., A 1)
• ncn_ref=54 The number reference for a National Cycle Network. See Cycle_routes
• ref=A 3;A 7 Default for more than one reference (German and French references with a space; e.g., A 1)
• alt_ref=* In South Africa certain roads share a primary and secondary reference numbers. The primary reference number is attributed in ref=* and the alt_ref=* is used for the continuation of the secondary reference number.

There are no global standards as to whether refs should include spaces, hyphens or other characters. At least when nationally consistent, tag what's on the ground. Some countries use spaces on the signs, others don't. In some countries the usage on the signs varies and guidelines are under discussion. Special cases:

• In the United States, some of the most popular ref formats do not correspond to what's on the ground, due to historical technical reasons. For example, Interstate highways are tagged e.g. ref=I 75 instead of ref=I-75, and some states use postal abbreviations instead of more ambiguous, human-readable prefixes such as "SR". However, this Sophox query demonstrates how a data consumer can automatically generate human-readable refs using the network=* tag on route relations.
• In e.g. the Netherlands there is a visual space on signs for readability, yet overwhelming usage in writing in both official and unofficial documents/websites/newspapers etc. is without spaces, hence the tagging is also without spaces.

It may seem redundant to tag route refs on both ways and relations, but do not remove a ref=* tag from a way just because the way is a member of corresponding route relations:

• Mainstream renderers and routers are still unable to infer refs from parent relations, so the way refs are needed for backwards compatibility.
• In some localities, one cannot predict the order that concurrent routes are listed on a sign based on the route relations alone. A regional route may be listed before a national route if the national route only briefly joins the road before diverging. In these cases, ref=* on the way is the only way to indicate the signposted order along that way, since a way does not indicate an intrinsic order to the routes of which it is a member.
• It is possible that not all ways with the ref are also part of the route for the ref. For example, it is possible that side roads and link roads are not a logical part of the road route, yet they may still belong to the same road reference (sometimes with a distinct carriageway_ref=*).
• The ref-value on the route may sometimes differ from the ref-value on the way. The ref-value on the way might need to be more verbose because it lacks the context of other tags on the route relation, such as network=*.

In runways of airports (aeroway=runway) this tag is used for the runway designator (for example "ref=02/20" or "ref=09L/27R").

Unsigned reference numbers (e.g. New York State Reference Route Numbers) that are neither readily visible on the ground nor well-known by the public, should be placed in unsigned_ref=* rather than ref=*. If the numbering system is specifically intended for internal use by the highway authority only, highway_authority_ref=* may be used.

Examples on nodes

A ref on a node generally means a highway exit when combined with highway=motorway_junction:

• ref=23 US Highway exits are often just a number
• ref=23B Sometimes exits have been split into A and B exits.

These refs can also be tagged on the adjoining highway=motorway_link way (or highway=trunk_link, highway=secondary_link, etc.) using junction:ref=*. In general, renderers understand ref=* on nodes, while routers understand junction:ref=* on ways.

ref is sometimes used on bus stops:

• ref=107309

ref is sometimes used to label an entrance into a large building or parking area. (If the label is used in addresses, consider using addr:unit=* instead.) For example a shopping mall may have entrances A - L:

• ref=A

Special uses

• ref=* - Used to mark official company store number assigned to a place. Example (ref=7872) CVS (You'll see a reference tag added to the building)
• ref:svhl=* - station-keys of Lübecker Stadtverkehr (Germany) - details look at Lübeck/Importe
• ref:luebeck=* - internal reference for objects in the area of Lübeck
• ref:bufa=* - 4-digit key of the local German tax and revenue offices (Bundesfinanzamtnummer)
• ref:vatin=CC12345678 - VAT identification number of companies, use CountryCode (e.g. IT for Italy) and the number
• official_ref=* - Used in cases where the official administrative reference for a road (or other feature) is not identical with the road signs (or other feature ref), e.g. because they are old, or because the administration doesn't have the money to install/update the signage.
• ref:penndot=* - Used for internal state route designations of the Location Referencing System in Pennsylvania.
• The approval of the boundary=forest_compartment clarified the meaning of the ref key when applied to forest compartments: in such cases, ref's value must be the one displayed on the ground and the unique ref of the compartment within the encompassing delimited forest, not a ref which is valid in, or applies to, a broader area. See boundary=forest_compartment for more details.

Authority control

Taking a page from Wikipedia, "in information science, authority control is a process that organizes information, for example in library catalogs, by using a single, distinct spelling of a name (heading) or a numeric identifier for each topic".^[60]. In OpenStreetMap, authority control is currently implemented by specifying the ID for map elements from a reference catalog as values for tags, using keys such as:

• ref=*: Generic ID of an unspecified catalog to be inferred by the map user based on the element type and circumstances
• *_ref=* and ref:*=* (like the keys listed above): ID to a specific catalog
• wikidata=*: Wikidata
• wikipedia=*: Wikipedia
• ISO3166-1=* and ISO3166-1:*=*: ISO country codes
• ISO3166-2=*: ISO province/state/region codes
• other domain-specific tags

Notes

• For highways shared by more than one route see Relations/Routes or Faq#What shall I do for roads that have multiple values for a tag?. Relations seem to be the preferred method for tagging this.
• If more than one reference is given, you are recommended to separate them with a semicolon and without a space character, because this is the widely established syntax in Germany and maybe other countries. But note, this syntax is being heavily discussed in Germany. A better approach might be to have a namespace and add the entity that has issued the ref, e.g. ref:foo=x ref:bar=y.
• Do not confuse this issue with the space that is present in some countries between the letter and the number in a reference itself.
• When a road has no number, leave this key unused; this makes sure that routing programs do not try to describe the road by a number.

Possible tagging mistakes

See also

• route_ref=* - route reference (number/code) cognizable on public transport stop signs
• local_ref=* - local reference/local platform
• junction:ref=* – motorway exit number
• ref:FR:*=*: WikiProject France/Liste des références nationales
• bridge:ref=*
• ref:US:EPA=*: United States EPA facilities registration codes

For United States road tagging

• addr:unit=* – used in cases where the label of a building entrance is used in addresses

References