restructure library documentation

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

diff --git a/docs/api/Faq.md b/docs/api/Faq.md
index 86f0e7835484628a9702cf23df610ba9b3368a79..c4a64d849b80d6947ae7ecd3ba019ede4be6b42f 100644 (file)
--- a/docs/api/Faq.md
+++ b/docs/api/Faq.md
@@ -35,7 +35,7 @@ it contains the county/state/country across the border.
 #### 3. I get different counties/states/countries when I change the zoom parameter in the reverse query. How is that possible?
 
 This is basically the same problem as in the previous answer.
-The zoom level influences at which [search rank](https://wiki.openstreetmap.org/wiki/Nominatim/Development_overview#Country_to_street_level) Nominatim starts looking
+The zoom level influences at which [search rank](../customize/Ranking.md#search-rank) Nominatim starts looking
 for the closest object. So the closest house number maybe on one side of the
 border while the closest street is on the other. As the address details contain
 the address of the closest object found, you might sometimes get one result,
@@ -58,4 +58,28 @@ The [Overpass API](https://wiki.openstreetmap.org/wiki/Overpass_API) is more
 suited for these kinds of queries.
 
 That said if you installed your own Nominatim instance you can use the
-`/utils/export.php` PHP script as basis to return such lists.
+`nominatim export` PHP script as basis to return such lists.
+
+#### 7. My result has a wrong postcode. Where does it come from?
+
+Most places in OSM don't have a postcode, so Nominatim tries to interpolate
+one. It first look at all the places that make up the address of the place.
+If one of them has a postcode defined, this is the one to be used. When
+none of the address parts has a postcode either, Nominatim interpolates one
+from the surrounding objects. If the postcode is for your result is one, then
+most of the time there is an OSM object with the wrong postcode nearby.
+
+To find the bad postcode, go to
+[https://nominatim.openstreetmap.org](https://nominatim.openstreetmap.org)
+and search for your place. When you have found it, click on the 'details' link
+under the result to go to the details page. There is a field 'Computed Postcode'
+which should display the bad postcode. Click on the 'how?' link. A small
+explanation text appears. It contains a link to a query for Overpass Turbo.
+Click on that and you get a map with all places in the area that have the bad
+postcode. If none is displayed, zoom the map out a bit and then click on 'Run'.
+
+Now go to [OpenStreetMap](https://openstreetmap.org) and fix the error you
+have just found. It will take at least a day for Nominatim to catch up with
+your data fix. Sometimes longer, depending on how much editing activity is in
+the area.
+