Merge remote-tracking branch 'upstream/master'

[nominatim.git] / docs / api / Output.md

diff --git a/docs/api/Output.md b/docs/api/Output.md
index c8589f6420aef638320f13fb6b899bc62a7ae46c..a37cbe0b820f565198a6cc8d7ede0fe81118aca0 100644 (file)
--- a/docs/api/Output.md
+++ b/docs/api/Output.md
@@ -2,12 +2,10 @@
 
 The [/reverse](Reverse.md), [/search](Search.md) and [/lookup](Lookup.md)
 API calls produce very similar output which is explained in this section.
 
 The [/reverse](Reverse.md), [/search](Search.md) and [/lookup](Lookup.md)
 API calls produce very similar output which is explained in this section.

-There is one section for each format which is selectable via the `format`
-parameter.
+There is one section for each format. The format correspond to what was
+selected via the `format` parameter.

 
 

-## Formats
-
-### JSON
+## JSON

 
 The JSON format returns an array of places (for search and lookup) or
 a single place (for reverse) of the following format:
 
 The JSON format returns an array of places (for search and lookup) or
 a single place (for reverse) of the following format:


@@ -41,13 +39,13 @@ a single place (for reverse) of the following format:
       "wikipedia": "en:London",
       "population": "8416535"
     }
       "wikipedia": "en:London",
       "population": "8416535"
     }

-  },
+  }

 ```
 
 The possible fields are:
 
  * `place_id` - reference to the Nominatim internal database ID ([see notes](#place_id-is-not-a-persistent-id))
 ```
 
 The possible fields are:
 
  * `place_id` - reference to the Nominatim internal database ID ([see notes](#place_id-is-not-a-persistent-id))

- * `osm_type`, `osm_id` - reference to the OSM object
+ * `osm_type`, `osm_id` - reference to the OSM object ([see notes](#osm-reference))

  * `boundingbox` - area of corner coordinates ([see notes](#boundingbox))
  * `lat`, `lon` - latitude and longitude of the centroid of the object
  * `display_name` - full comma-separated address
  * `boundingbox` - area of corner coordinates ([see notes](#boundingbox))
  * `lat`, `lon` - latitude and longitude of the centroid of the object
  * `display_name` - full comma-separated address


@@ -62,22 +60,22 @@ The possible fields are:
  * `geojson`, `svg`, `geotext`, `geokml` - full geometry
    (only with the appropriate `polygon_*` parameter)
 
  * `geojson`, `svg`, `geotext`, `geokml` - full geometry
    (only with the appropriate `polygon_*` parameter)
 

-### JSONv2
+## JSONv2

 
 This is the same as the JSON format with two changes:
 
  * `class` renamed to `category`
  * additional field `place_rank` with the search rank of the object
 
 
 This is the same as the JSON format with two changes:
 
  * `class` renamed to `category`
  * additional field `place_rank` with the search rank of the object
 

-### GeoJSON
+## GeoJSON

 
 This format follows the [RFC7946](https://geojson.org). Every feature includes
 a bounding box (`bbox`).
 
 
 This format follows the [RFC7946](https://geojson.org). Every feature includes
 a bounding box (`bbox`).
 

-The feature list has the following fields:
+The properties object has the following fields:

 
  * `place_id` - reference to the Nominatim internal database ID ([see notes](#place_id-is-not-a-persistent-id))
 
  * `place_id` - reference to the Nominatim internal database ID ([see notes](#place_id-is-not-a-persistent-id))

- * `osm_type`, `osm_id` - reference to the OSM object
+ * `osm_type`, `osm_id` - reference to the OSM object ([see notes](#osm-reference))

  * `category`, `type` - key and value of the main OSM tag
  * `display_name` - full comma-separated address
  * `place_rank` - class search rank
  * `category`, `type` - key and value of the main OSM tag
  * `display_name` - full comma-separated address
  * `place_rank` - class search rank


@@ -92,13 +90,13 @@ The feature list has the following fields:
 Use `polygon_geojson` to output the full geometry of the object instead
 of the centroid.
 
 Use `polygon_geojson` to output the full geometry of the object instead
 of the centroid.
 

-### GeocodeJSON
+## GeocodeJSON

 
 The GeocodeJSON format follows the
 [GeocodeJSON spec 0.1.0](https://github.com/geocoders/geocodejson-spec).
 The following feature attributes are implemented:
 
 
 The GeocodeJSON format follows the
 [GeocodeJSON spec 0.1.0](https://github.com/geocoders/geocodejson-spec).
 The following feature attributes are implemented:
 

- * `osm_type`, `osm_id` - reference to the OSM object (unofficial extension)
+ * `osm_type`, `osm_id` - reference to the OSM object (unofficial extension, [see notes](#osm-reference))

  * `type` - value of the main tag of the object (e.g. residential, restaurant, ...)
  * `label` - full comma-separated address
  * `name` - localised name of the place
  * `type` - value of the main tag of the object (e.g. residential, restaurant, ...)
  * `label` - full comma-separated address
  * `name` - localised name of the place


@@ -110,18 +108,18 @@ The following feature attributes are implemented:
 Use `polygon_geojson` to output the full geometry of the object instead
 of the centroid.
 
 Use `polygon_geojson` to output the full geometry of the object instead
 of the centroid.
 

-### XML
+## XML

 
 The XML response returns one or more place objects in slightly different
 formats depending on the API call.
 
 
 The XML response returns one or more place objects in slightly different
 formats depending on the API call.
 

-#### Reverse
+### Reverse

 
 ```
 <reversegeocode timestamp="Sat, 11 Aug 18 11:53:21 +0000"
                 attribution="Data © OpenStreetMap contributors, ODbL 1.0. https://www.openstreetmap.org/copyright"
                 querystring="lat=48.400381&lon=11.745876&zoom=5&format=xml">
 
 ```
 <reversegeocode timestamp="Sat, 11 Aug 18 11:53:21 +0000"
                 attribution="Data © OpenStreetMap contributors, ODbL 1.0. https://www.openstreetmap.org/copyright"
                 querystring="lat=48.400381&lon=11.745876&zoom=5&format=xml">

-  <result place_id="179509537" osm_type="relation" osm_id="2145268" ref="BY"
+  <result place_id="179509537" osm_type="relation" osm_id="2145268" ref="BY" place_rank="15" address_rank="15"

           lat="48.9467562" lon="11.4038717"
           boundingbox="47.2701114,50.5647142,8.9763497,13.8396373">
        Bavaria, Germany
           lat="48.9467562" lon="11.4038717"
           boundingbox="47.2701114,50.5647142,8.9763497,13.8396373">
        Bavaria, Germany


@@ -148,7 +146,7 @@ attribution to OSM and the original querystring.
 The place information can be found in the `result` element. The attributes of that element contain:
 
  * `place_id` - reference to the Nominatim internal database ID ([see notes](#place_id-is-not-a-persistent-id))
 The place information can be found in the `result` element. The attributes of that element contain:
 
  * `place_id` - reference to the Nominatim internal database ID ([see notes](#place_id-is-not-a-persistent-id))

- * `osm_type`, `osm_id` - reference to the OSM object
+ * `osm_type`, `osm_id` - reference to the OSM object ([see notes](#osm-reference))

  * `ref` - content of `ref` tag if it exists
  * `lat`, `lon` - latitude and longitude of the centroid of the object
  * `boundingbox` - comma-separated list of corner coordinates ([see notes](#boundingbox))
  * `ref` - content of `ref` tag if it exists
  * `lat`, `lon` - latitude and longitude of the centroid of the object
  * `boundingbox` - comma-separated list of corner coordinates ([see notes](#boundingbox))


@@ -159,14 +157,14 @@ The full address of the result can be found in the content of the
 Additional information requested with `addressdetails=1`, `extratags=1` and
 `namedetails=1` can be found in extra elements.
 
 Additional information requested with `addressdetails=1`, `extratags=1` and
 `namedetails=1` can be found in extra elements.
 

-#### Search and Lookup
+### Search and Lookup

 
 ```
 <searchresults timestamp="Sat, 11 Aug 18 11:55:35 +0000"
                attribution="Data © OpenStreetMap contributors, ODbL 1.0. https://www.openstreetmap.org/copyright"
                querystring="london" polygon="false" exclude_place_ids="100149"
                more_url="https://nominatim.openstreetmap.org/search.php?q=london&addressdetails=1&extratags=1&exclude_place_ids=100149&format=xml&accept-language=en-US%2Cen%3Bq%3D0.7%2Cde%3Bq%3D0.3">
 
 ```
 <searchresults timestamp="Sat, 11 Aug 18 11:55:35 +0000"
                attribution="Data © OpenStreetMap contributors, ODbL 1.0. https://www.openstreetmap.org/copyright"
                querystring="london" polygon="false" exclude_place_ids="100149"
                more_url="https://nominatim.openstreetmap.org/search.php?q=london&addressdetails=1&extratags=1&exclude_place_ids=100149&format=xml&accept-language=en-US%2Cen%3Bq%3D0.7%2Cde%3Bq%3D0.3">

-  <place place_id="100149" osm_type="node" osm_id="107775" place_rank="15"
+  <place place_id="100149" osm_type="node" osm_id="107775" place_rank="15" address_rank="15"

          boundingbox="51.3473219,51.6673219,-0.2876474,0.0323526" lat="51.5073219" lon="-0.1276474"
          display_name="London, Greater London, England, SW1A 2DU, United Kingdom"
          class="place" type="city" importance="0.9654895765402"
          boundingbox="51.3473219,51.6673219,-0.2876474,0.0323526" lat="51.5073219" lon="-0.1276474"
          display_name="London, Greater London, England, SW1A 2DU, United Kingdom"
          class="place" type="city" importance="0.9654895765402"


@@ -203,11 +201,12 @@ The place information can be found in the `place` elements, of which there may
 be more than one. The attributes of that element contain:
 
  * `place_id` - reference to the Nominatim internal database ID ([see notes](#place_id-is-not-a-persistent-id))
 be more than one. The attributes of that element contain:
 
  * `place_id` - reference to the Nominatim internal database ID ([see notes](#place_id-is-not-a-persistent-id))

- * `osm_type`, `osm_id` - reference to the OSM object
+ * `osm_type`, `osm_id` - reference to the OSM object ([see notes](#osm-reference))

  * `ref` - content of `ref` tag if it exists
  * `lat`, `lon` - latitude and longitude of the centroid of the object
  * `boundingbox` - comma-separated list of corner coordinates ([see notes](#boundingbox))
  * `ref` - content of `ref` tag if it exists
  * `lat`, `lon` - latitude and longitude of the centroid of the object
  * `boundingbox` - comma-separated list of corner coordinates ([see notes](#boundingbox))

- * `place_rank` - class search rank
+ * `place_rank` - class [search rank](../develop/Ranking#search-rank)
+ * `address_rank` - place [address rank](../develop/Ranking#address-rank)

  * `display_name` - full comma-separated address
  * `class`, `type` - key and value of the main OSM tag
  * `importance` - computed importance rank
  * `display_name` - full comma-separated address
  * `class`, `type` - key and value of the main OSM tag
  * `importance` - computed importance rank


@@ -217,17 +216,19 @@ When `addressdetails=1` is requested, the localised address parts appear
 as subelements with the type of the address part.
 
 Additional information requested with `extratags=1` and `namedetails=1` can
 as subelements with the type of the address part.
 
 Additional information requested with `extratags=1` and `namedetails=1` can

-be found in extra elements as sub-element of each place.
+be found in extra elements as sub-element of `extratags` and `namedetails`
+respectively.

 
 
 ## Notes on field values
 
 ### place_id is not a persistent id
 
 
 
 ## Notes on field values
 
 ### place_id is not a persistent id
 

-The `place_id` is created when a Nominatim database gets installed. A
-single place will have a different value on another server or even when
-the same data gets re-imported. It's thus not useful to treat it as
-permanent for later use.
+The `place_id` is an internal identifier that is assigned data is imported
+into a Nominatim database. The same OSM object will have a different value
+on another server. It may even change its ID on the same server when it is
+removed and reimported while updating the database with fresh OSM data.
+It is thus not useful to treat it as permanent for later use.

 
 The combination `osm_type`+`osm_id` is slighly better but remember in
 OpenStreetMap mappers can delete, split, recreate places (and those
 
 The combination `osm_type`+`osm_id` is slighly better but remember in
 OpenStreetMap mappers can delete, split, recreate places (and those


@@ -236,20 +237,40 @@ Places can also change their meaning without changing their `osm_id`,
 e.g. when a restaurant is retagged as supermarket. For a more in-depth
 discussion see [Permanent ID](https://wiki.openstreetmap.org/wiki/Permanent_ID).
 
 e.g. when a restaurant is retagged as supermarket. For a more in-depth
 discussion see [Permanent ID](https://wiki.openstreetmap.org/wiki/Permanent_ID).
 

-Nominatim merges some places (e.g. center node of a city with the boundary
-relation) so `osm_type`+`osm_id`+`class_name` would be more unique.
+If you need an ID that is consistent over multiple installations of Nominatim,
+then you should use the combination of `osm_type`+`osm_id`+`class`.
+
+### OSM reference
+
+Nominatim may sometimes return special objects that do not correspond directly
+to an object in OpenStreetMap. These are:
+
+* **Postcodes**. Nominatim returns an postcode point created from all mapped
+  postcodes of the same name. The class and type of these object is `place=postcdode`.
+  No `osm_type` and `osm_id` are included in the result.
+* **Housenumber interpolations**. Nominatim returns a single interpolated
+  housenumber from the interpolation way. The class and type are `place=house`
+  and `osm_type` and `osm_id` correspond to the interpolation way in OSM.
+* **TIGER housenumber.** Nominatim returns a single interpolated housenumber
+  from the TIGER data. The class and type are `place=house`
+  and `osm_type` and `osm_id` correspond to the street mentioned in the result.
+
+Please note that the `osm_type` and `osm_id` returned may be changed in the
+future. You should not expect to only find `node`, `way` and `relation` for
+the type.

 
 ### boundingbox
 
 Comma separated list of min latitude, max latitude, min longitude, max longitude.
 The whole planet would be `-90,90,-180,180`.
 
 
 ### boundingbox
 
 Comma separated list of min latitude, max latitude, min longitude, max longitude.
 The whole planet would be `-90,90,-180,180`.
 

-Can we used to pan and center the map on the result, for example with leafletjs
+Can be used to pan and center the map on the result, for example with leafletjs

 mapping library
 `map.fitBounds([[bbox[0],bbox[2]],[bbox[1],bbox[3]]], {padding: [20, 20], maxzoom: 16});`
 
 Bounds crossing the antimeridian have a min latitude -180 and max latitude 180,
 mapping library
 `map.fitBounds([[bbox[0],bbox[2]],[bbox[1],bbox[3]]], {padding: [20, 20], maxzoom: 16});`
 
 Bounds crossing the antimeridian have a min latitude -180 and max latitude 180,

-essentially covering the planet (See [issue 184](https://github.com/openstreetmap/Nominatim/issues/184)).
+essentially covering the entire planet
+(see [issue 184](https://github.com/openstreetmap/Nominatim/issues/184)).

 
 ### addressdetails
 
 
 ### addressdetails