Commons:Machine-readable data

On Wikimedia Commons, a lot of metadata (including license and author) are not machine readable. There is an API module, iiprop=extmetadata which can be used to retrieve some values (example), but as the information is entered as free text into the file description page itself, this is not perfect. The ongoing Structured data on Commons project aims to move the metadata as fully-structured data and will eventually supersede the machine-readable data presented in this page.

In the meantime, and to ease a transition towards more structured data at a future time, Wikimedia Commons use a set of standard templates which have been made machine-readable in some ways, through HTML elements. Some scripts already make use of that. It is worth noting that this data is available for any wiki using Wikimedia Commons, where it can be read from the html of the File: page just as other local data.

Machine readable data

Machine readable data set by infobox templates

These are several standard infobox templates tagging different elements of the template with different tags to allow parsing of the information. Several different styles of tags are used:

Microformat tags follow industry standards and can be parsed by already existing tools.
<td> id attributes (identifiers) are custom markings which allow more complete tags, which have to be read by custom tools. Most universal infoboxes have two column structure: column #1 holds name of the field and column #2 holds the value
- Traditionally <td> id attributes were used to tag the name call in the first column in a row. To get the data, you would need to get the contents of the following <td> cell in the second column.
- {{Creator}} and {{Institution}} templates have more complicated structure, so the cells with the actual data are tagged with attributes using magenta background.

Template	Template parameter name	Description	<td> id attribute	Microformat	Comment
{{Information}}	description	file description	`fileinfotpl_desc`	hProduct.description.	Often contains multiple languages annotated with {{Lang}}.
{{Information}}	date	date the original work was created	`fileinfotpl_date`	hCalendar vevent.dtstart	Sometimes additionally, or only, contains publication date. These two dates have different meanings for copyright. When used, {{Date context}} can indicate the difference. Microformat added by {{Date}} template
{{Information}}	source	file's source	`fileinfotpl_src`		Often contains entire tables. We have no good way to deal with this source templates yet. Source templates often have references to catalogue IDs, but these are also not machine readable.
{{Information}}	author	file's author	`fileinfotpl_aut`		This can be author, creator and/or copyright holder and is used mixed. Often contains the {{Creator}} template which is described below.
{{Information}}	permission	permission/license for the file	`fileinfotpl_perm`
{{Information}}	other versions	other versions of the file	`fileinfotpl_ver`
{{Artwork}}	description	description of the artwork	`fileinfotpl_desc`	hProduct.description
{{Artwork}}	date	date of creation of the original artwork	`fileinfotpl_date`	hCalendar vevent.dtstart	microformat added by {{Date}} template
{{Artwork}}	source	file's source	`fileinfotpl_src`
{{Artwork}}	artist	creator of the artwork	`fileinfotpl_aut`	"hProduct.fn value"
{{Artwork}}	author	author of the artwork	`fileinfotpl_aut`	"hProduct.fn value"
{{Artwork}}	permission	permission/license for the file and artwork	`fileinfotpl_perm`
{{Artwork}}	other versions	other versions of the file	`fileinfotpl_ver`
{{Artwork}}	title	title of the artwork	`fileinfotpl_art_title`	hProduct.fn
{{Artwork}}	object type	artwork object type	`fileinfotpl_art_object_type`
{{Artwork}}	medium	technique or medium of the artwork	`fileinfotpl_art_medium`
{{Artwork}}	dimensions	dimensions of the artwork	`fileinfotpl_art_dimensions`
{{Artwork}}	gallery	institution holding the artwork	`fileinfotpl_art_gallery`
{{Artwork}}	location	location of the artwork within the institution	`fileinfotpl_art_location`	hProduct.locality
{{Artwork}}	accession number	accession number of the artwork	`fileinfotpl_art_id`	hProduct.identifier
{{Artwork}}	object history	object history of the artwork	`fileinfotpl_art_object_history`
{{Artwork}}	exhibition history	exhibition history of the artwork	`fileinfotpl_art_exhibition_history`
{{Artwork}}	credit line	credit line of the artwork	`fileinfotpl_art_credit_line`
{{Artwork}}	inscriptions	inscriptions on the artwork	`fileinfotpl_art_inscriptions`
{{Artwork}}	notes	notes about the artwork	`fileinfotpl_art_notes`
{{Artwork}}	references	references related to the artwork	`fileinfotpl_art_references`
{{Book}}	Author	author of the book	`fileinfotpl_author`
{{Book}}	Editor	editor of the book	`fileinfotpl_book_editor`
{{Book}}	Translator	translator of the book	`fileinfotpl_book_translator`
{{Book}}	Illustrator	illustrator of the book	`fileinfotpl_book_illustrator`
{{Book}}	Title	title of the book	`fileinfotpl_book_title`
{{Book}}	Subtitle	subtitle of the book	`fileinfotpl_book_subtitle`
{{Book}}	Series title	series-title of the book	`fileinfotpl_book_series-title`
{{Book}}	Authority file	authority control data	`fileinfotpl_book_authority`
{{Book}}	Publisher	publisher of the book	`fileinfotpl_book_publisher`
{{Book}}	Printer	printer of the book	`fileinfotpl_book_printer`
{{Book}}	Year of publication	date or year of the publication of the book	`fileinfotpl_date`
{{Book}}	Place of publication	place or city of the publication of the book	`fileinfotpl_book_place-of-publication`
{{Book}}	Language	language of the book	`fileinfotpl_book_language`
{{Book}}	Description	description of the book	`fileinfotpl_desc`
{{Creator}}	Name	Name of creator	`creator`	vCard.fn
{{Creator}}	Alternative names	Alternative names of creator	`fileinfotpl_creator_alt-name_value`	vCard.nickname
{{Creator}}	Description	Nationality and occupation(s) of creator	`fileinfotpl_creator_desc_value`	vCard.note
{{Creator}}	Date of death	Date of death of creator	`fileinfotpl_creator_deathdate_value`
{{Creator}}	Date of birth	Date of birth of creator	`fileinfotpl_creator_birthdate_value`	vCard.bday
{{Creator}}	Location of birth/death	Location of death of creator	`fileinfotpl_creator_deathloc_value`
{{Creator}}	Location of birth	Location of birth of creator	`fileinfotpl_creator_birthloc_value`
{{Creator}}	Work period	Work period of creator	`fileinfotpl_creator_work-period_value`
{{Creator}}	Work location	Work location of creator	`fileinfotpl_creator_work-location_valuev`
{{Creator}}	Image	portrait or photo showing the creator	`fileinfotpl_creator_image`
{{Creator}}	Authority file	Authority control related to the creator	`fileinfotpl_creator_authority_value`
{{FileContentsByBot}}	(various)	depends, please confer {{FileContentsByBot}}	`(various)`	hproduct-by-bot	big data set and still growing, please confer {{FileContentsByBot}}
{{Photograph}}	title	title of the photograph	`fileinfotpl_art_title`	hProduct.fn
{{Photograph}}	description	description of the photograph	`fileinfotpl_desc`	hProduct.description
{{Photograph}}	original description	original archival description of the photograph	`fileinfotpl_desc`	hProduct.description
{{Photograph}}	date	date of creation of the original artwork	`fileinfotpl_date`	hCalendar vevent.dtstart	microformat added by {{Date}} template
{{Photograph}}	medium	technique or medium of the photograph	`fileinfotpl_art_medium`
{{Photograph}}	dimensions	dimensions of the photograph	`fileinfotpl_art_dimensions`
{{Photograph}}	artist	creator of the photograph	`fileinfotpl_aut`	"hProduct.fn value"
{{Photograph}}	institution	institution holding the artwork	`fileinfotpl_art_gallery`
{{Photograph}}	location	location of the photograph within the institution	`fileinfotpl_art_location`	hProduct.locality
{{Photograph}}	source	file's source	`fileinfotpl_src`
{{Photograph}}	permission	permission/license for the file and artwork	`fileinfotpl_perm`
{{Photograph}}	other versions	other versions of the file	`fileinfotpl_ver`
{{Photograph}}	accession number	accession number of the photograph		hProduct.identifier

Alternative format for CommonsMetadata

Because the table + id based format proved very hard to add to templates which were not formatted similarly to the Commons information template, CommonsMetadata allows an alternative format, similar to license templates: the whole information template has to be enclosed in a fileinfotpl class and the tag containing the specific information needs to have a fileinfotpl_* class (same names as above, but class, not id).

Machine readable data set by license templates

Introduced in October 2010, using classes 

licensetpl: An element identifying a license. Wraps the entire license code and should be a SINGLE license, not a multi license.
licensetpl_short: Short name of the license: “Public domain”, “CC BY-SA 3.0”, “CC by 2.0 fr”, etc.
licensetpl_long: Long name of the license: “Public domain”, “Creative Commons Attribution-Share Alike 3.0”,
licensetpl_attr_req: Whether attribution is required. “true” or “false”.
licensetpl_attr: The requested attribution: Free text.
licensetpl_link_req: Whether a link to the license is required for this license. “true” or “false”.
licensetpl_link: The link to the license deed. “www.creativecommons.org/licenses/by-sa/XXX/YYY”
licensetpl_nonfree: “true“ if this is a non-free license (not used on Commons, only on wikis with an EDP)

Multiple licensetpl blocks for the same work might be wrapped in a block using the class licensetpl_wrapper.

Templates setting this information

Templates setting licensetpl include: {{PD-Layout}}, {{Cc-by-sa-3.0-migrated}}, {{Cc-by-layout}}, {{Cc-by-sa-layout}}, {{Cc-zero}}, {{FAL}}, {{GFDL}}, {{GFDL-1.2}}, {{GPL}} and {{LGPL}}.

Machine readable data set by style formatting templates

Style formatting templates, meant to provide uniform styles to different families of non-license templates, carry machine readable data identifying these families.

Template	Purpose	class name
{{Restriction-Layout}}	used by Restriction tags	`restrictiontemplate`
{{FoP-Layout}}	used by freedom of panorama tags	`foptemplate`
{{Partnership-Layout}}	used by Partnership templates	`partnershiptemplate`
{{Source-Layout}}	used by generic Source templates	`sourcetemplate`
{{Created with}}	used by Created with ... templates	`createdwithtemplate`

Machine readable data set by non-copyright restriction templates

Templates regarding non-copyright legal restrictions carry these classes to identify specific types of restrictions.

Template(s)	Purpose	class name
{{Trademarked}}	Trademarked images	`restriction-trademarked`
{{Copydesign}}	Copyrighted designs	`restriction-design`
{{Communist symbol}}	Communist symbols	`restriction-communist`
{{Italy-MiBAC-disclaimer}} {{Soprintendenza}}	Italian cultural goods	`restriction-ita-mibac`
{{Australian Commonwealth reserve}}	Australian reserves	`restriction-aus-reserve`
{{Personality rights}} {{Romania personality rights}}	Personality rights	`restriction-personality`
{{2257}}	Child Protection and Obscenity Enforcement Act warning (United States)	`restriction-2257`
{{Costume}}	Costuming	`restriction-costume`
{{Fan art}}	Fan art	`restriction-fan-art`
{{Currency}}	Currency	`restriction-currency`
{{IHL Symbol}}	Symbols restricted by International Humanitarian Law	`restriction-ihl`
{{Nazi symbol}}	Nazi and fascist symbols	`restriction-nazi`
{{Insignia}}	Official insignia	`restriction-insignia`

Machine readable data set by specific templates

More machine-readable data are set. Here is a non-exhaustive list:

{{Personality rights}}: Personality rights
{{Credit line}}: <td id="fileinfotpl_credit" class="fileinfo-paramfield fileinfotpl_credit" style=""></td>

Machine-readable data set by location templates

{{Location}} and similar templates add machine-readable geocodes in the following format: 12.34;24.68 (latitude and longitude as floating-point numbers, separated by a semicolon). The coordinates use the en:WGS84 system (same as the GPS and most online maps). See Commons:Geocoding for more details.

Usage

MediaWiki API

The MediaWiki API now serves a limited number of metadata. Consider the following query:

/w/api.php?action=query&prop=imageinfo&format=json&iiprop=extmetadata&iilimit=5&titles=File%3AFranziskanerkirche%20Salzburg%20panoramic%20view%20interior%2039252px.jpg

(Open in API Sandbox) that returns some useful parameters such as Credit, Artist, LicenseUrl and Copyrighted and is used by Media Viewer, for example.

Scripts using machine-readable data

External tools

Defining new machine readable data

Do NOT use HTML id's, use classes. An ID can only be used once per page and most of these fields can occur multiple times per page. Consider for instance descriptions of derivative works, which can include information about the original and the derivative.
When possible, wrap the actual data, not some field header. This last method is historically used for all our Information templates, but much harder to support in the long run.
Wrap data, not the way the data is formatted.
Expect that formatting is lost when converting to data. Visual dress up is not part of the information.
Don't wrap multiple units of information inside one field. There is a difference between a publication date and a creation date. Both are dates, but both are different 'data fields'. Also CC BY-SA-4.0-3.0-2.5 is not a license name, those would be 3 licenses with the name CC BY-SA-##.
Make sure that the data value has one unit, or outputs one consistent unit.

Problems

There are a few things that are currently NOT or badly recognizable. These include:

Derivative works
Works included in works. See also Category:FoP_templates
licenses derivates or works included in works are a mess.
Author vs. Copyright holder
usernames vs 'real names'
Catalogue IDs etc
VRTS permissions
Publication date vs creation date
Donating institutions of materials
Anything that is NOT using the above structures is not recognizable at all and will require manual cleanup at some point.
Heirs: {{Heirs-license}}
Multilicensed CC works, that use {{Cc-by-3.0,2.5,2.0,1.0}}, {{Cc-by-sa-2.5,2.0,1.0}}, {{Cc-by-sa-4.0,3.0,2.5,2.0,1.0}} or {{Cc-by-all}}.
Non-licensed works: {{Copyrighted free use}}, {{Attribution}} (Problem, how to describe this grant of rights success ?)
Improvised File description templates like User:Tevaprapas/Information
Templates denoting the copyright of partials of the work: {{Copyright information}}