OSM Inspector/Views/Tagging

From OpenStreetMap Wiki
Jump to navigation Jump to search

The Tagging view in OSM Inspector shows basic problems with tag keys and values.


Anybody can use any tag keys and any tag values for any OSM object. This gives us an enormous flexibility but also leads to a lot of cruft like misspelled tags accumulating in the database. Older tags that are not in use any more could be deleted, tags that contain FIXME messages can be worked upon. This layer shows several of those cases.

Data sources

All data in this view is derived from OSM data.

Data for the whole world is available in this view.

The OSM data processing of this view is done by osmi_simple_views.


These layers are available in two variants, one for nodes and one for ways:

Empty tag key

The Empty tag key layers show all nodes/ways with tags having an empty key. This should not happen in normal operations.

Empty tag value

The Empty tag value layers show all nodes/ways with tags having an empty value. This should not happen in normal operations.

Tag key with space

The Tag key with space layers show nodes/ways having a whitespace character such as a space, tabulator key or carriage return in a key. This should be avoided to make tag usage easier for everybody. Note that whitespace in tag values is perfectly ok.

Unusual character

The Unusual character layers show nodes/ways with unusual characters in their tag keys. Of course, unusual doesn't mean its wrong, but in many cases somebody just hit the wrong key. Unusual is everything thats not a normal letter (in any Unicode alphabet), number or some special characters like the colon (:) often used in tag keys.

Unusual key length

The Unusual key length layer shows any nodes/ways with keys with only one or two characters or keys with 50 or more characters. This is not forbidden, but unusual. Generally keys should be self-explanatory. Very short keys are hard to understand. (For instance what should they key id mean? Probably some kind of identifier, but what?) Very long keys are hard to use and in most cases are probably the result of an error somewhere. Automated edits are strongly discouraged unless you really know what you are doing!

Tagged with FIXME

The Tagged with FIXME layers highlight all nodes/ways with tags of the following forms:

todo=* Everything with key todo (lower case).
fixme=* Everything with key fixme (lower case) or FIXME (upper case).
*=FIXME Every tag whose value is FIXME in any case.

If you zoom in far enough a label with the tag is shown.

The following layers are only available for ways:

Ways without tags

The Ways without tags layer shows all ways without any tags that are not in a relation. The relation must have one of the following tags:

Either some tags have to be added (preferably) or the way could be deleted.

Hidden non-operational tagging

The layer hidden non-operational tagging shows ways and nodes all the following rules apply to:

These rules catch combinations like highway=secondary + construction=yes where a minor tag such as construction=yes inverts the meaning of a major tag. They are ignored by most but not all data consumers and therefore lead to wrong interpretations. construction=* and similar tags should only be used if the main tag has the value construction, i.e. highway=construction + construction=secondary.

Name/description without feature tags

It occurs rather often that newbies add objects to OSM without proper tags. They manage to add a name, a description and/or a website but that’s it. This is caused by both a lack of experience and a suboptimal user interface of the editor being used (and in rare cases a lack of suitable tags). These objects are more or less hidden from any data consumer because nobody wants to parse the value of a name or description tag to guess what it represents.

OSMI distinguishes between non-feature keys and feature keys. A key is considered a non-feature key if it begins with one of the following strings:

  • name
  • description
  • comment
  • website
  • contact:website
  • and some more. See also the full list in the source code.

The following keys are considered being feature keys, i.e. they describe what the object represents:

building, landuse, highway, railway, amenity, shop, natural, waterway, power, barrier, leisure, man_made, tourism, boundary, public_transport, sport, emergency, historic, route, aeroway, place, craft, entrance, playground, aerialway, healthcare, military, building:part, training, traffic_sign, xmas:feature, seamark:type, waterway:sign, university, pipeline, club, golf, junction and more keys (see the source code)

The office=* tag is only a feature tag if it has a value other than yes.

All other keys are considered being neutral and do not influence the evaluation.

If an object has a non-feature key but no feature key, it is flagged as an error.

This layer can be useful to find spam in OSM.

Removed Layers

The Misspelled key ? layers show nodes/ways with possibly misspelled tag keys. The check is performed as follows: The commonness of all keys in the database is counted. Then all keys which are seen less then 10 times are compared to all keys seen more than 1000 times. If they are similar, this might indicate a misspelled key. Similarity is checked according to the Levensthein algorithm. This check will miss many false keys and it will have false positives, ie. it will flag some keys that are perfectly ok. Always check objects manually and use common sense before correcting objects based on this tag. This layer was removed on 2017-06-19. Use the Similar tab of Taginfo instead.

The Unwayed segments layer is relic from the past. OSM used to have segments, short lines connecting exactly two nodes. We got rid of them in autumn 2007 with the change from API 0.4 to API 0.5. All the segments that were in the database on switchover day were converted into ways and got tagged as unwayed segments. All those ways will show up in this layer. They should be checked, maybe aggregated into longer ways and then the FIXME tag removed. This layer was removed on 2017-06-19 after it has been empty for a few years.

What you can do with this view to improve OSM data

All layers in this view show you things that need fixing. In many cases the problems are obvious once you look at the offending tag and the other tags on an object and you can fix it without even knowing the area.

For the Empty tag key and Empty tag value layers you can probably just remove the tag.

In the Tag key with space, Misspelled key?, and Unusual key length layers you will probably spot many obvious misspellings which you can fix. If you don't know the tags or tagged objects it might be better to leave things alone, though.

Look for Ways without tags in your area and add tags where you know or can infer what tags are meant. Only remove those ways if they are obviously redundant or silly.


See also