Data items are a way to document all OSM metadata like keys and tags in every language on this wiki in a structured way, useful to both humans and tools.
- Tools, such as iD editor and Taginfo are now able to get tag information by parsing data items instead of parsing the wiki markup. Eventually the data may include translations, tag suggestions, validation rules, common pitfalls, presets, and more.
- This wiki can now show data as info cards and tables, without information duplication and complicated template hackery.
- At cost of introducing new interface with own complexity and pitfalls
- All metadata can be in analyzed using Sophox queries (see query examples).
This page documents how to store structured tag metadata on this wiki using data items provided by the Wikibase extension - the same software that runs Wikidata (initial discussion). Wikidata's glossary is helpful for understanding the structure and terminology of data items. However, this project's goal is NOT to replace the OSM Wiki pages (including infoboxes), nor to use opaque IDs instead of the human readable key=value strings to tag features. We are only trying to improve metadata documentation, making it more useful to various tools.
Where to find them
Data items are located in the Item: namespace. Each data item has a page title consisting of a "Q" followed by a numeric ID.
Every Key: and Tag: page has a corresponding data item. Follow the "Data item" link in the "Tools" section of the page's sidebar, or enter the page's title into Special:ItemByTitle/wiki/.
How to help
- Add tag descriptions and translations. See the following 3 minute video.
Every item should have statements describing the item, but the properties you use depend on the subject matter. More properties can be added over time; to propose a property, start a discussion on the talk page and notify a data administrator once there is consensus.
|description||string||en - The mechanism by which a movable bridge moves to clear the way below.
uk - Механізм, що приводить в дію рухомий міст для вивільнення шляху під ним.
|This is the primary way to describe the key using proper sentences that end with a period, and whose first word is capitalized. Must not contain any wiki markup or HTML. Must be less than 250 symbols. When translating, it is usually enough to add just the description to the item. Any key:... and tag:...=... will be automatically shown as links.|
||Key/tag data items: add labels only to English. Don't add labels in other languages (use Aliases).
Labels can and should be added in all languages to items which are not key or tag pages.
No longer active bot was setting the English label to the key's value, exactly the same as P16 below. Some languages have nativekey (localized key) that was added to the labels as well. Do not add a copy of the English label to any other languages. Note that same as "en", the localized label must be unique in that language.
|sitelink||string||Key:bridge:movable||Links to the Key:... pages, even if the page does not exist. The sitelink is shown on top of the page on the other side as the page title.|
|instance of (P2)
||Item||key (Q7)||Indicates that the item represents a key.|
|permanent key ID (P16)
||Shows the exact form of the key as used in OSM. Must never be changed once the item is created. Due to technical limitations, keys "Key:water tap", "Key:water_tap", and "Key:water_tap_" have identical wiki pages/sitelinks - "Key:water tap". In this case, set this property to multiple strings, but mark one as "Preferred rank".|
|applies to nodes (P33)
||Item||is applicable (Q8000)
||Sets if this key is allowed on nodes/ways/areas/relations. In the future we may want to use other statuses like approved (Q15), but this is not yet supported. See also limiting per locale below.|
|image (P28) [ image caption (P47) ]
||An image stored either on Wikimedia Commons (preferable) or on the OSM wiki, without the File: prefix. If people in different regions would only recognize the key when illustrated using different images, add multiple images and qualify each image with limited to region (P48). If the key's image contains anything language-specific, add another value and set limited to language (P26). Make sure to set Preferred rank status for the default image. Use image caption (P47) qualifier to indicate image caption for any language (will show English if not found, or any other if EN does not exist).|
||Item||bridges (Q4712)||The group this item belongs to. In the current model, each key belongs to just one group. In theory we could use it to attach multiple groups, changing the meaning of the "group" to something like a "label"/"meta-tag".|
|status (P6) [ proposal discussion (P11) ]
|community's approval status, together with a reference link to the discussion page (optional)|
|key type (P9)
||Item||well-known values (Q8)||Describes the type of values this key is expected to have. If there is a well known list of values, use Q8. Other types are TBD.|
|Wikidata concept (P12)
||Item||Q787417||A link to the Wikidata item, stored as an external ID (string). Must be a Q-number.|
|value validation regex (P13)
||A regular expression that can be used to validate the value of this key. In this case the value must be one or more digits. Validators will require the entire expression to match the string, i.e. they will add |
See population (Q574) example.
|documentation wiki pages (P31)
||multilingual string||Key:bridge:movable (English)
|Each value is the name of the wiki page in a specific language.
Note: After setting this property, use Special:SetSiteLink to set a sitelink to the English page name on the site
|required key or tag (P22)
|different from (P18)
Key prefixes and suffixes
Each key prefix (namespace) or key suffix (subkey) is stored much like a key, except that you specify permanent key prefix ID (P52) or permanent key suffix ID (P53) instead of
permanent key ID (P16). For example, not: (Q19669) describes not:*=* and :conditional (Q22164) describes *:conditional=*:
|instance of (P2)
||Item||key prefix (Q22020) or key suffix (Q22021)||Indicates that the item represents a key prefix or key suffix, respectively.|
|permanent key prefix ID (P52)
||Shows the exact form of the key prefix as used in OSM, not including any wildcard characters or delimiters. Must never be changed once the item is created.|
|permanent key suffix ID (P53)
||Shows the exact form of the key suffix as used in OSM, not including any wildcard characters or delimiters. Must never be changed once the item is created.|
For keys like Key:highway, there is a list of the well-known values such as highway=residential, highway=service, highway=footway. These values are stored similarly to keys. See bridge:movable=bascule (Q888) that describes a bridge:movable=bascule. See all items that link to bridge:movable.
|description||string||en - A type of movable bridge, a bascule bridge contains one or two spans, one end of which is free and swings upwards. A counterweight at the pivoting end of the span or spans balances the weight as the free end rises.
pl - Most zwodzony jest to rodzaj mostu w którym co najmniej jedno przęsło jest podnoszone. Mosty zwodzone mogą być jedno- lub dwuskrzydłowe.
|This is the primary way to describe a tag using proper sentences (first word capitalized, ending with a period). Must not contain any wiki markup or HTML. Must be less than 250 symbols. When translating, it is usually enough to add just the description to the item. Any key:... and tag:...=... will be automatically shown as links.|
||Label usage is still a bit undecided for the key/tag data items, so it is best not to use it for anything. No longer active bot was setting the English label to the tag's value, exactly the same as P19 below. Some languages have nativekey=nativevalue (localized key/value) that was added to the labels as well. Do not add a copy of the English label to any other languages. Note that same as "en", the localized label must be unique in that language.|
|sitelink||string||Tag:bridge:movable=bascule||Links to the Tag:... pages, even if the page does not exist. The sitelink is shown on top of the page on the other side as the page title.|
|instance of (P2)||Item||tag (Q2)||Indicate the type of the item. Set to Q2 for tags.|
|permanent tag ID (P19)||string||
||Shows the exact form of the tag as used in OSM. Must never be changed once the item is created. Due to technical limitations, tags "Tag:water tap=yes", "Tag:water_tap=yes", and "Tag:water_tap=yes_" have identical wiki pages/sitelinks - "Tag:water tap=yes". In this case, set this property to multiple strings, but mark one as "Preferred rank" (small up arrow left of value).|
|key for this tag (P10)||Item||bridge:movable (Q104)||Every tag item links to the corresponding key item, making it easier to query and validate.|
Tags may also use applies to nodes (P33), applies to ways (P34), applies to areas (P35), applies to relations (P36), image (P28), group (P25), status (P6), value validation regex (P13), documentation wiki pages (P31), implies (P45). See their description in Tag Key section above.
|description||string||...||This is the primary description of the relation, using proper sentences that end with a period with the capitalized first word. Must not contain any wiki markup or HTML. Must be less than 250 symbols. When translating, it is usually enough to add just the description to the item. Any key:... and tag:...=... will be automatically shown as links.|
||Short relation description. Do not add a copy of the English label to any other languages.|
|sitelink||string||Relation:restriction||Links to the corresponding Relation:... wiki page, even if the page does not exist. The sitelink is shown on top of the page on the other side as the page title.|
|instance of (P2)||Item||relation type (Q6)||Indicate the type of the item. Must be set to Q6 for relations.|
|permanent relation type ID (P41)
||Shows the exact form of the relation type as used in OSM. Must never be changed once the item is created. Due to technical limitations, sitelinks "Relation:destination sign", "Relation:destination_sign", and "Relation:destination_sign_" have identical wiki sitelink - "Relation:destination sign". In this case, set this property to multiple strings, but mark one with a Preferred rank.|
|tag for this relation type (P40)
||Item||type=restriction (Q16013)||Every relation item links to the corresponding type=* tag item, making it easier to query and validate.|
Members of the relation could be labeled with "roles", e.g. "inner" and "outer" ways in the multipolygon relation. Each role for each relation type has its own data item. Example for boundary=admin_centre (Q16060).
|description||string||...||This is the primary description of the relation role, using proper sentences that end with a period with the capitalized first word. Must not contain any wiki markup or HTML. Must be less than 250 symbols. When translating, it is usually enough to add just the description to the item. Any key:... and tag:...=... will be automatically shown as links.|
||Short relation role description. Do not add a copy of the English label to any other languages.|
|sitelink||string||Relation:boundary=admin centre||Links to the Relation:<relation>=<role> wiki page, even if the page does not exist. If the role is empty, use Relation:relation= form. If the role has a variable portion, e.g. route=platform:<number>, set sitelink to the fixed part -- Relation:route=platform:, and use value validation regex (P13) to validate the variable part. The sitelink is shown on top of the page on the other side as the page title.|
|instance of (P2)||Item||relation member role (Q4667)||Indicate the type of the item. Must be set to Q4667 for the relation member roles.|
|permanent relation role ID (P21)
||Shows the exact form of the relation role as used in OSM but preceded by "<relationtype>=". Must never be changed once the item is created. Due to technical limitations, sitelinks "Relation:boundary=admin_centre", "Relation:boundary=admin centre", and "boundary=admin_centre_" have identical wiki sitelink - "Relation:boundary=admin centre". In this case, set this property to multiple strings, but mark one with a Preferred rank.|
|belongs to relation type (P43)
||Item||boundary relation (Q16019)||Every relation member role links to the corresponding relation item, making it easier to query and validate.|
|value validation regex (P13)
||A regular expression that can be used to validate the variable part of the role. In this case the value must be one or more digits, e.g. for the route=platform:<number> role. Validators will convert regex expression into the |
Relation member roles may also use applies to nodes (P33), applies to ways (P34), applies to areas (P35), applies to relations (P36), image (P28), group (P25), status (P6), documentation wiki pages (P31). See their description in the Tag Key section above.
Storing geographical differences
A phone booth looks very different depending on the geographical region, e.g. a country. To indicate that an image, or any other value of the data item is specific to a location, use limited to region (P48) qualifier with a geographical region item.
Storing locale differences
Tag:... pages tend to have mismatching parameters like status, group, or the types of elements it should be used on. While some were deliberate results after a careful local community evaluation (see noexit (Q501)), many other cases are simply stale and need to be fixed, or possibly removed from the template's parameters to let it use the underlying data item.
All locale differences are stored using limited to language (P26). The value with no qualifiers is the default. It should have the Preferred rank, but it is OK to keep Normal rank when there are no other values for the property. All language-specific values must use limited to language (P26) and have Normal rank. Each value must be used only once, possibly with multiple qualifier values (e.g. a property "applies to nodes (P33)" can have only one "is applicable (Q8000)" and one "is not applicable (Q8001)"). Each language qualifier can only be used once for the whole property. Language must not be listed if it is the same as the default. If there is no value without qualifiers, it means that the default is not set (e.g. English page has no onRelation= parameter).
|group (P25)||bridges (Q4712)||no qualifiers||This value is used for English page and all other language pages except those explicitly listed below.|
|properties (Q4671)||limited to language (P26)||This value is only used for the Italian and Finnish pages.|
|placement (Q4707)||limited to language (P26)||This value is only used for the Czech pages.|
There are many data items which are neither a Key nor a Tag:
- OSM Concepts
- element (Q9), key (Q7), tag (Q2), status (Q11), group (Q12)
- Statuses of type status (Q11)
- de facto (Q13), in use (Q14), approved (Q15), voting (Q17), proposed (Q20), obsolete (Q5060), deprecated (Q5061), discardable (Q7550), imported (Q21146)
- Statuses of type applicability of a key/tag to a specific element type (Q8010)
- is applicable (Q8000), is not applicable (Q8001)
- OpenStreetMap concept (Q10), Sandbox (Q2761)
Item creation process
Current methods for creating new items
- Special:NewItem -- please use Wiki search in namespace "Item" only (do not prefix with `Key:` or `Tag:) and Special:ItemByTitle/wiki/ (use the `Key:` or `Tag:` prefix, e.g. `Key:highway` or `Tag:highway=residential`) to do a search so that duplicate items are not added.
- The JOSM `osmwiki-dataitem` plugin -- right click on the tag entry, `Create new WikiData item for <key or tag>`, and follow the prompts. If only `Open WikiData for <key or tag>` is visible, then the item already exists in wiki data or the key is not marked as a well-defined key (for example, `note` or `name` will not be marked as `P9=Q8` (key type=well defined)). The wikidata plugin currently only supports `Tag` and `Key` types.
While the JOSM wikidata plugin is currently in alpha, it does add more information than the Special:ItemByTitle/wiki page, so it may be easier and better to use the plugin over the special page at this time.
In the event that Special:ItemByTitle/wiki is used, please add the following information:
- instance of (tag, key, relation, relation role)
- permanent id (key, tag, relation, relation role)
- documentation wiki pages
- Set the sitelink at Special:SetSiteLink for the newly created item (`Site ID` should most likely be `wiki`, the `ID` should be the `Q` identifier, for example `Q335`, and the sitelink should be the identifier, e.g. `Key:highway).
- This is needed so that Special:ItemByTitle/wiki works properly
A bot has created all significantly used keys and tags, and continued creating these items when they were detected in the OSM database (taginfo API) or on the wiki. The bot used to:
- create an item for any key with 10+ usages if it matches
^[a-z0-9]+([-:_\.][a-z0-9]+)*$(i.e. sequence of one or more words separated by single dashes, colons, underscores or periods, where words contain only lower case English letters and numbers), or for any 1000+ usages regardless of the key syntax (see talk page)
- set item's label to be the same as the key
- set item's description from the corresponding wiki page's info card (if available, from all languages)
- set used-on, recommended tags, implies, and any other easy-to-figure-out data from the info cards.
- will NOT update any fields modified by a user, e.g. if description in FR has been changed by a user, it should not be changed by the bot.
Eventually, it would be better for OSM tools (iD, JOSM, ...) to ask the user for the metadata, and use MW API to create new items.
Item deletion process
Data items can be deleted manually by administrators. They might delete a Data Item if
- there is no regular wiki page here (aside from discussions or user pages) that describe a key/tag/rel/... and
- there is no proposal associated with the Data Item and
- the Data Item does not qualify for creation according to the Item Creation Process.
If you accidentally create a duplicate item, ask a data administrator to merge it with the preexisting one. The duplicate item will become a redirect to minimize impact on data consumers.
API access and querying
An external tool can get all the data about a given key or tag in several ways:
- Use Special:ItemByTitle/wiki to determine the key or tag's QID, then use Special:EntityData to get a dump of the item in a supported format. For example, barrier=hedge (Q4918): Special:ItemByTitle/wiki/Tag:barrier=hedge, then Special:EntityData/Q4918.json.
- The same process can be streamlined in a
languagesto filter labels and descriptions to the needed languages.
- There are more existing actions you can use when working with Data Items. These API actions can be found in the MediaWiki (Data Items) API help (search there for a string starting with
wbwhich is the abbreviation for wikibase.
- Use Sophox to query metadata. There are some metadata-specific examples.
Tracking changes to data items
To track changes to data items, you can add a data item to your Watchlist like any other page on the wiki. You can also configure your Watchlist to automatically include changes to the data item associated with any wiki page you are watching, by opening the "Filter changes (use menu or search for filter name)" dropdown and checking the "Data item edits" checkbox. To make these changes permanent, click the button or checking the "Show data item edits in your watchlist" checkbox in your watchlist preferences.
Changes to data items are included in Special:RecentChanges, Special:RecentChangesLinked, and Special:Watchlist by default. To filter out all edits to data items, click the Namespaces button in the filter panel, check "Item", and click "Exclude selected". To filter out changes to labels, descriptions, or aliases but include changes to statements, click the Tags button in the filter panel, check "Data item terms", and click "Exclude selected". (This latter filter is useful for ignoring translations and is implemented via an "abuse filter" and corresponding tag.)
To make any of these changes permanent, click the button.
There are several additional extensions designed to validate Wikibase data, and find items that do not pass validation. Installing such capabilities may not be done in the first deployment stage.
Note that due to limitations listed in section below watchlisting data items is dysfunctional. As result, lower number of editors monitors data items. In case of conflict between data item data and data on OSM Wiki page in the infobox, it is very likely that data item is incorrect.
Limitations and known issues
- Wikibase's "Commons File" properties do not yet support files stored on this wiki. Instead, we use a regular string property to store the image name, and use a gadget (see your preferences) to show strings as images.
- The sitelink in the upper right corner does not show whether the Tag:* or a Key:* page exists or not.
- All sitelinks must use spaces instead of underscores. API sitelink search does not work otherwise. See permanent key ID (P16) and permanent tag ID (P19) for the correct value. Note that regular Mediawiki Key:* and Tag:* pages have the same issue, and use a special hack to change the title.
- MediaWiki removes spaces/underscores from the key, so Key:_abc_ would become Key: abc. There are no way to have two items with sitelinks Key:_abc and Key:_abc_ -- they are treated as the same, and fail.
- Date item titles and talk page titles are not human readable, e.g. Item:Q5007 vs Tag:amenity=shelter
- Item "Q" numbers collide with those used in the main Wikidata site, e.g. wikidata Q5007 vs dataitem Q5007). Despite numerous attempts by OSM community, and a working implementation by Yurik, the fix for this issue was declined by the maintainers of the Wikibase software. They suggest that the distinction should be done via a prefix.
- The Wikibase software and the Wikidata project are sometimes confused with these data items, which in the past have been called "the wikibase" or "wiki data items" by some users.
Adding a data item to the Special:Watchlist will generate more watchlist notification, including all language translations.
Because of this, many experienced wiki users and mappers are not following the data item pages, so any mistakes are less likely to be fixed as quickly as mistakes on Tag and Key wiki pages.
This is tracked as T43686 on Wikidata issue tracker.
The current data item editing experience should be improved, especially in these areas:
- Most data items were created by bot, and used to be updated by bot, unless a human user has edited the item. The bot source code is available, but undocumented.
- Editing data item should be made simpler by a direct edit button from the key/tag/relation page, without navigating to the data item page itself. An experimental data item editor can already be enabled in user preferences, but there is more work to be done in polishing this feature. (Source code)
- Currently there is no bulk-editing interface available, other than to write a bot. We should enable Quick Statements tool to simplify such operations.
- The current system of having the tag description in two places (wiki page and data items) has been creating some problems. The difference is shown by a small icon, and can also be queried in Sophox (TODO: add query link here).
- It is not currently possible to copy the data item content, edit it outside browser as text, and copy it back, or to make multiple changes to a data item at one time.
- In some cases editing an article page (for example to delete a wrong field from the Infobox) will result in the data item taking over. As result, after a user removed the parameter the same wrong data is still displayed. As result people editing infobox parameters now need to also edit data items.
- Editing data item is not resulting in immediate update of wiki page, ?action=purge is needed what is confusing for a typical user (especially in cases mentioned above where wiki page was polluted by invalid data from data item)
- Use of data items to generate infoboxes results in confusing view of old page state, as they will reflect not state of data item at time of edit but current data item state
It is technically feasible to delete parameters from infoboxes on OSM Wiki pages and display infobox using just data item. But there is no support for doing this kind of edits. There may be support for such action among people translating a given language.
- Sandbox (Q2761) is a sandbox item - feel free to make any changes to it.
- All available properties
- technical site configuration details
- Wikibase Registry has an entry for OSM Wiki as Item Q26.
- OSM Semantic Network