Property talk:P921
Documentation
primary topic of a work (see also P180: depicts)
| Description | Primary topic of a work. See also depicts (P180) for depicted items or minor subjects and characters (P674). | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Represents | topic (Q200801), matter (Q26256810), subject (Q12310021) | ||||||||||||
| Data type | Item | ||||||||||||
| Domain | According to this template:
published works - work (Q386724)
According to statements in the property:
When possible, data should only be stored as statementswork (Q386724), group of humans (Q16334295), cross-reference (Q1302249), genre (Q483394), event (Q1656682), course (Q600134), intellectual property (Q131257), artistic theme (Q1406161), theme restaurant (Q676586), grant (Q230788), clinical trial (Q30612), criminal investigation (Q1964968), content rating category (Q23649976), scandal (Q192909), information leak (Q2904148), archival collection (Q9388534), collection (Q2668072), paraphilia (Q178059), lesson (Q379833), inquiry (Q21004260), hashtag (Q278485), research project (Q1298668), experiment (Q101965), aspect of history (Q17524420), introduction (Q305178), project (Q170584), goal (Q4503831), media campaign (Q62090711), biological pathway (Q4915012), learned society (Q955824), meme (Q978), bibliography (Q134995), school subject (Q362165), scientific theory (Q3239681), concept (Q151885), theme park (Q2416723), item of collection or exhibition (Q18593264), Wikipedia article covering multiple topics (Q21484471), oral communication (Q3689704), list (Q12139612), Wikimedia list article (Q13406463), Wikimedia project page (Q14204246), saying (Q3026787), proposition (Q108163), WikiProject (Q16695773), intentional human activity (Q451967), history (Q309), archetype (Q131714), public inquiry (Q20669447), concrete object (Q4406616), discourse (Q190539), identifier (Q853614), online community (Q6576792), rule (Q1151067), YouTube channel (Q17558136), social media account (Q102345381), software resource (Q110832782), academic discipline (Q11862829), fictional rule (Q55421512), community (Q177634), attraction (Q2800000), suicide (Q10737), campaign (Q6056746), reform (Q900406), incentive program (Q382996), library collection (Q856592), statement (Q2684591), message (Q628523), exhibition (Q464980), information campaign (Q4202233), conflict (Q180684), legal case (Q2334719), fictional work (Q124301146), matter (Q26256810) or academic degree (Q189533) | ||||||||||||
| Usage notes | primary topic of a work. Should not be confused with genre (P136), which relates creative works to their genres like science fiction (Q24925) | ||||||||||||
| Example | Marina (Q14915757) → Rocco Granata (Q1345844) De historia stirpium commentarii insignes (Q948923) → plant (Q756) Metaphysics (Q661655) → metaphysics (Q35277) | ||||||||||||
| Tracking: usage | Category:Pages using Wikidata property P921 (Q20990008) | ||||||||||||
| Tracking: local yes, WD no | no label (Q101364456) | ||||||||||||
| See also | depicts (P180), facet of (P1269), genre (P136), category's main topic (P301), narrative motif (P6962), review of (P6977), commemorates (P547), template has topic (P1423), digital representation of (P6243) | ||||||||||||
| Lists | |||||||||||||
| Proposal discussion | Proposal discussion | ||||||||||||
| Current uses |
| ||||||||||||
| Search for values |
List of violations of this constraint: Database reports/Constraint violations/P921#Type Q386724, Q16334295, Q1302249, Q483394, Q1656682, Q600134, Q131257, Q1406161, Q676586, Q230788, Q30612, Q1964968, Q23649976, Q192909, Q2904148, Q9388534, Q2668072, Q178059, Q379833, Q21004260, Q278485, Q1298668, Q101965, Q17524420, Q305178, Q170584, Q4503831, Q62090711, Q4915012, Q955824, Q978, Q134995, Q362165, Q3239681, Q151885, Q2416723, Q18593264, Q21484471, Q3689704, Q12139612, Q13406463, Q14204246, Q3026787, Q108163, Q16695773, Q451967, Q309, Q131714, Q20669447, Q4406616, Q190539, Q853614, Q6576792, Q1151067, Q17558136, Q102345381, Q110832782, Q11862829, Q55421512, Q177634, Q2800000, Q10737, Q6056746, Q900406, Q382996, Q856592, Q2684591, Q628523, Q464980, Q4202233, Q180684, Q2334719, Q124301146, Q26256810, Q189533, SPARQL
List of violations of this constraint: Database reports/Constraint violations/P921#Conflicts with P31, search, SPARQL
Replacement property: intended public (P2360)
Replacement values: (Help)
List of violations of this constraint: Database reports/Constraint violations/P921#none of, SPARQL
Replacement property:
Replacement values: Afrocentrism (Q1876790) (Help)
List of violations of this constraint: Database reports/Constraint violations/P921#none of, SPARQL
List of violations of this constraint: Database reports/Constraint violations/P921#Conflicts with P31, SPARQL
Replacement property:
Replacement values: (Help)
List of violations of this constraint: Database reports/Constraint violations/P921#none of, SPARQL
Replacement property:
Replacement values: (Help)
List of violations of this constraint: Database reports/Constraint violations/P921#none of, SPARQL
|
Value josei (Q503106) will be automatically replaced to value josei (Q503106) and moved to intended public (P2360) property. Testing: TODO list |
|
|
Value shōjo (Q242492) will be automatically replaced to value shōjo (Q242492) and moved to intended public (P2360) property. Testing: TODO list |
|
|
Value children's anime and manga (Q478804) will be automatically replaced to value children's anime and manga (Q478804) and moved to intended public (P2360) property. Testing: TODO list |
|
|
Value shōnen (Q231302) will be automatically replaced to value shōnen (Q231302) and moved to intended public (P2360) property. Testing: TODO list |
|
|
Value seinen (Q237338) will be automatically replaced to value seinen (Q237338) and moved to intended public (P2360) property. Testing: TODO list |
|
|
Value General Mathematics (Q60111089) will be automatically replaced to value mathematics (Q395). Testing: TODO list |
|
|
Value Mechanics of Materials (Q64320918) will be automatically replaced to value condensed matter physics (Q214781). Testing: TODO list |
(Help)
Violations query:
SELECT ?item ?itemLabel ?itemDescription { ?item wdt:P31 wd:Q13442814 ; rdfs:label "Obituary"@en . FILTER NOT EXISTS { ?item wdt:P921 [] } SERVICE wikibase:label { bd:serviceParam wikibase:language "en" } } LIMIT 200List of this constraint violations: Database reports/Complex constraint violations/P921#Missing statement with property on article items labeled "Obituary"
(Help)
Violations query:
SELECT ?item ?itemLabel ?itemDescription { ?item wdt:P31 wd:Q13442814 ; rdfs:label "OBITUARY"@en . FILTER NOT EXISTS { ?item wdt:P921 [] } SERVICE wikibase:label { bd:serviceParam wikibase:language "en" } } LIMIT 200List of this constraint violations: Database reports/Complex constraint violations/P921#Missing statement with property on article items labeled "OBITUARY"
Redundancy with depicts (P180)[edit]
Sorry, I did not take the time to discuss the property before creation, but I do not think it is useful to have both this property and depicts (P180). Yes, "depicts" sounds better for a visual work "main topic" sounds better for a text, but the meaning is the same; The only difference is that this one is only the "main" topic while "depicts" is more inclusive. But I think that what constitutes the main of secondary topic would be better expressed by statement ranks than by separate properties. --Zolo (talk) 07:58, 10 October 2013 (UTC)
- >> further debate: Property talk:P180#Ambiguous
Using it for other stuff[edit]
I would like to start mapping conflicts around the construction of hydropower plants. I am uncertain about which property to use in order to link a conflict to hydropower (Q170196) though (e.g. Occupation of the Hainburger Au (Q829823)). In lack of another property, I thought about using this one here. However, then the description of the property would have to change into a more general one, less centered on creative works. --Shikeishu (talk) 21:57, 19 September 2016 (UTC)
More than one statement per work possible[edit]
Should this property be used more than once for a work item? Or is there a better property to state several topics the work deals with? In particular I would like to express that e.g. a video game treats topics like mass murder, martyrdom and arial warfare. --Dmainz (talk) 20:03, 4 November 2016 (UTC)
- I'm not sure an item for a video game should be using this property at all... It's not really that kind of creative work, with a topic.
- In general, though, I think it's acceptable for there to be more than one P921 statement in an item. --Yair rand (talk) 21:40, 14 August 2017 (UTC)
- But how many? I'd be favoring adding a constraint only allowing up to three to five items linked with this. -- Discostu (talk) 06:18, 18 May 2020 (UTC)
- This is an interesting question. I conducted a quick search and found this excerpt from the Sears List of Subject Headings, 21st Edition:
- "Many books are about more than one subject. In that case a second or third subject heading is necessary. Theoretically there is no limit to the number of subject entries that could be made for one work, but in practice an excess of entries is a disservice to the user of the catalog. More than three subject headings should be assigned to a single item only after careful consideration. The need for more than three may be due to the cataloger’s inability to identify precisely the single broader heading that would cover all the topics in the work. Similarly, a subject heading should not be assigned for a topic that comprises less than one third of a work."
- Fjjulien (talk) 23:23, 15 December 2021 (UTC)
- But how many? I'd be favoring adding a constraint only allowing up to three to five items linked with this. -- Discostu (talk) 06:18, 18 May 2020 (UTC)
Apply for classes[edit]
Should this property only apply to instances of selected items or should apply to subclasses too? It seems to me that depicts (P180): Pokémon species (Q3966183) is a correct statement for Pokémon video game (Q55588631). Right now it is suggested as an issue by the integrated tool.
--Ogoorcs (talk) 19:44, 16 July 2018 (UTC)
discrepancy between name, description, and use of the property[edit]
The name "main subject" is rather misleading for how this property is being used. To me, and apparently to other people (see above), on the face of it "main" sounds like it should be the overall themes that are throughout a work. Yet, there are good reasons to note down some of the sub-topics of a work, and this property is the only one available to do that. For instance, suppose an article about the Second Anglo-Sikh War has 3.5 interesting pages about the Siege of Jellalabad, you might want to have a way of indicating the existence of this piece of writing about the siege, and P921 comes to the rescue. (Or, an article I just read, "Bude Haven and the Wreck of the Bencoolen," is literally half apiece about those two topics.) No doubt there's a discussion somewhere in the archives about what should be the default name for this property, and people had their reasons for choosing "main subject" rather than "subject." But I suggest changing the description from "primary topic of a work" to something like "important topic in a work." Levana Taylor (talk) 05:13, 3 October 2019 (UTC)
Support I totally agree and we should just change the property name to simply "subject". In Schema.org we have "about" (for all applicable subjects) and then "mainEntity" (for the main subject its about). But here in Wikidata, we have ranking https://www.wikidata.org/wiki/Help:Ranking which can take care of that easily without needing 2 properties, where Preferred rank can be used to note the "main" subjects from any Normal rank "secondary" subjects.
- There are currently no constraints on the number of subjects that could be applied with this property, and I feel that's a good thing. I think the initial fear from the archives I read was around "SEO" abuse?, but that doesn't seem to have happened much, and now can easily be caught (for instance querying "creative works" that have more than 10x P921 statements, if we so desire later on).
- Normal rank could effectively be used against that fear to show neutrality against lots of extra secondary subjects:
- Normal ranks are typically used for statements that contain relevant information that is believed to be correct, but may be too extensive to be shown by default.
- Preferred rank is a great way to show consensus around multiple primary or main subjects:
- The preferred rank is assigned to the most current statement or statements that best represent consensus (be it scientific consensus or the Wikidata community consensus).
- I also agree with you that the description could be changed perhaps to "primary topics of a work" to help folks understand that multiple applicable subjects could be applied and even further expanded to note to users about simply "Please applying ranking if you wish to capture the primary (Preferred) and secondary (Normal) subjects."
Thadguidry (talk) 23:23, 11 July 2021 (UTC)
- I still feel that P921 (as it is worded now) is not an obvious choice for a detailed list of topics covered by an item, e.g. by non-fiction texts (scholarly work etc.). The labels (including the also known as) and descriptions clearly indicate preference for main, central subjects. For comparison, depicts (P180) or characters (P674) readily invite a detailed enumeration of elements dealt with by an item. P921 is not equivalent. I support changing the labels and description to clarify whether this property is intended to list only a handful (maybe 3-5) main subjects, or if it's intended for a detailed listing of all topics covered (distinguishing the main topics by rank, as suggested above by Thadguidry. Neither the property page nor the talk page explain this, leading to an inconsistent use.
- The second example in the documentation at the top of this page, De historia stirpium commentarii insignes (Q948923)main subject (P921)plant (Q756) is not a statement that's actually stated on the item page. And I think it would be a good thing to know which property to use when linking the actual plants covered by the historia stirpium commentarii insignes. --Jonas kork (talk) 14:36, 24 March 2022 (UTC)
Use of Mix-n-match to add main subject (P921) (mostly biography items)[edit]
See Help:Add main subject with Mix-n-Match. --- Jura 12:34, 2 April 2020 (UTC)
Proposal: Move all types of study to "uses"[edit]
The Source MetaData WikiProject does not exist. Please correct the name. The Source MetaData/More WikiProject does not exist. Please correct the name. Currently, this property is used to indicate the type of study. See this query. I propose moving those to uses (P2283). @jsamwrites: WDYT?--So9q (talk) 10:07, 28 September 2021 (UTC)
- uses (P2283) is also correct, especially when it's clear that the approach used is indeed cohort study (Q1778788). I also feel that such articles could be added as instances of (instance of (P31)) of cohort study (Q1778788). There are many such examples. For example, literature review (Q2412849), where I have used main subject (P921). I hesitated between instance of (P31) and main subject (P921). John Samuel (talk) 17:08, 28 September 2021 (UTC)
- How about describes a project that uses (P4510)? --- Jura 18:45, 28 September 2021 (UTC)
- Considering the examples given in the property describes a project that uses (P4510) page, I think describes a project that uses (P4510) is relevant for cohort study (Q1778788). (I do wonder whether a scholarly article can be considered as a project. Though, I agree that research/scholarly articles are the outcomes of some projects) John Samuel (talk) 19:57, 28 September 2021 (UTC)
- @Jsamwrites A scholarly article could definitely be considered as a project but usually it’s not a goal on itself but a depiction of another project such a scientific experiment. Maybe the described project includes an instance of cohort study (Q1778788). author TomT0m / talk page 13:10, 18 December 2021 (UTC)
- Considering the examples given in the property describes a project that uses (P4510) page, I think describes a project that uses (P4510) is relevant for cohort study (Q1778788). (I do wonder whether a scholarly article can be considered as a project. Though, I agree that research/scholarly articles are the outcomes of some projects) John Samuel (talk) 19:57, 28 September 2021 (UTC)
castle or castellogy[edit]
Before I change them, can I confirm that the aim here is to record the discipline, rather than the object, if words exist for both, so for books about castle (Q23413) we should be using castellology (Q2941393) ever though its a more obscure term. Vicarage (talk) 21:20, 30 September 2023 (UTC)
Past discussion on renaming this to "describes"[edit]
Wikidata Telegram discussion I thought would be notable/interesting to save here. Lectrician1 (talk) 23:50, 12 January 2024 (UTC)
- Could you please post the discussion here or give a summary? Thanks! - Valentina.Anitnelav (talk) 12:26, 13 January 2024 (UTC)
lectrician1, [6/18/2022 9:09 PM] Do we have a property like "talked about" for things people talked about on broadcasts?
lectrician1, [6/18/2022 9:11 PM] I guess there's P921
wikilinksbot, [6/18/2022 9:11 PM] P921 (https://www.wikidata.org/entity/P921) – main subject
lectrician1, [6/18/2022 9:11 PM] but I'd really like to rename that prop at this point
lectrician1, [6/18/2022 9:11 PM] "describes" would be sooooo much better
lectrician1, [6/18/2022 9:28 PM] How can I relate Q4376555 and Q112628344 to say that pre-orders can occur during the pre-order period?
wikilinksbot, [6/18/2022 9:28 PM] Q4376555 (https://www.wikidata.org/entity/Q4376555) – pre-order Q112628344 (https://www.wikidata.org/entity/Q112628344) – pre-order period
lectrician1, [6/18/2022 10:23 PM] I guess an analogous situation is voting : can occur during : voting period
Nikki, [6/18/2022 11:11 PM] "describes" would change the meaning...
lectrician1, [6/18/2022 11:27 PM] 🤷 it's one of the aliases right now. can you give an example that change would be important?
Kim, [6/19/2022 12:22 AM] I'd say that the onus is on you to prove there are no cases and not on Nikki to do that work for you.
Nikki, [6/19/2022 12:24 AM] just because it's an alias doesn't mean it works for everything
Nikki, [6/19/2022 12:36 AM] and I'd suggest starting by looking at the aliases or the most common types of entities it's used on, you should soon find some areas where it would be odd to say the main subject is being described
Nikki, [6/19/2022 12:42 AM] and "describes" completely misses out the "main" aspect of the property
lectrician1, [6/19/2022 10:47 AM] with "main" in the property name though it makes it seem as if there is only one thing that the thing is primarily about
মাহির মোরশেদ, [6/19/2022 10:48 AM] I do not see that implication at all
lectrician1, [6/22/2022 11:23 AM] Well, since someone agrees with me above, I'll elaborate.
We typically say: "The main subject of the presentation is JavaScript"
We don't say: "The main subject of the presentation is JavaScript, variables, functions, classes, and promises"
What's mainly talked about is Javascript.
What is described regardless of prominence are all of the other things and Javascript.
Nikki, [6/22/2022 11:28 AM] that doesn't mean there can't be multiple things that are part of the main subject
lectrician1, [6/22/2022 11:28 AM] Right but for cases like this, describes as the property name can cover less prominent subjects like above correctly.
Nikki, [6/22/2022 11:29 AM] but that's not how you're supposed to use it
lectrician1, [6/22/2022 11:29 AM] ok, so what property do I use instead?
Nikki, [6/22/2022 11:30 AM] I dunno, there probably isn't one that's so broad because people have a tendency to do ridiculous things
lectrician1, [6/22/2022 11:31 AM] I wanted one for this use
মাহির মোরশেদ, [6/22/2022 11:32 AM] I am generally opposed to using properties, usually "main subject" (for items) or "depicts" (for SDC), as any sort of catch-all tagging system
মাহির মোরশেদ, [6/22/2022 11:32 AM] and indeed this view does not conflict with that
Nikki, [6/22/2022 11:32 AM] like the way people use depicts on commons makes me cringe. it seems to be a mixture of people treating it as a generic keyword field, entering anything and everything even if it's not even related, and people who literally list every single thing depicted
Moebeus, [6/22/2022 11:32 AM] Speaking of: I found a few songs where every word in the lyrics ended up in "main subject". Turns out someone tried to map the relationship between the song and a speech given by Macron, French prez. Which, to be fair: pretty cool idea! Main subject not really the best way though, imo.
lectrician1, [6/22/2022 11:33 AM] @mahir256 do you agree with @moebeus here?
মাহির মোরশেদ, [6/22/2022 11:34 AM] indeed this seems a bit overkill, but unless the song is exclusively about the Macron speech, there could otherwise be more than one main subject on it
lectrician1, [6/22/2022 11:35 AM] idk we could propose a "describes" prop but if @mahir256 and likely others think "main subject" should catch everything and others do not, I'm not sure it will pass.
মাহির মোরশেদ, [6/22/2022 11:35 AM] where the hell did you get that from?
মাহির মোরশেদ, [6/22/2022 11:35 AM] por favor lee este mensaje otra vez
lectrician1, [6/22/2022 11:36 AM] > as any sort of catch-all tagging system
lectrician1, [6/22/2022 11:36 AM] idk elaborate if you want
মাহির মোরশেদ, [6/22/2022 11:36 AM] > I am generally opposed to using properties ... as any sort of catch-all tagging system
মাহির মোরশেদ, [6/22/2022 11:37 AM] two "main subjects" != "catch-all tagging"
Moebeus, [6/22/2022 11:37 AM] Oh, the song was not about any speech at all. It was written decades before Macron. The idea was more to show how Macron (or his speechwriters) rips of poets or something, not really sure
lectrician1, [6/22/2022 11:37 AM] oh shoot misread sorry
lectrician1, [6/22/2022 11:38 AM] sooooooooooooo propose "describes"?
lectrician1, [6/22/2022 11:38 AM] "for topics a work describes that are less prominent than the main subject"?
Moebeus, [6/22/2022 11:40 AM] "mentions" sounds closer to your examples than "describes" perhaps?
lectrician1, [6/22/2022 11:44 AM] Sure. I see the prop being particularly useful for describing the subsections of articles or presentations
James Heald, [6/22/2022 11:47 AM] I suggested something like this in 2019, but it didn't go anywhere: https://www.wikidata.org/wiki/Wikidata:Property_proposal/subject_facet
lectrician1, [6/22/2022 11:48 AM] You still had a lot of supports. Just not enough
lectrician1, [6/22/2022 11:49 AM] For talk sows where subjects are erraneous should they use main subject or mentions?
মাহির মোরশেদ, [6/22/2022 11:51 AM] if the subjects are err[o]neous shouldn't they be corrected?
- As this is somehow related to your need for a broad "describes" property: there were already some proposals of a "mentions"-property (all declined): Wikidata:Property_proposal/mentioned_in_work, Wikidata:Property_proposal/Mentioned_at, Wikidata:Property_proposal/mentions_named_entity. This may be helpful if you're still thinking about proposing a similar property. Kind regards, - Valentina.Anitnelav (talk) 17:58, 20 January 2024 (UTC)
- I've been using facet of (P1269) for those WP articles that talk about a subject, and have been erroneously labelled as a subclass of (P279) of it. Vicarage (talk) 18:05, 20 January 2024 (UTC)
- All Properties
- Properties with wikibase-item-datatype
- Properties used on 10000000+ items
- Properties with constraints on type
- Properties with conflicts with constraints
- Properties with entity type constraints
- Properties with scope constraints
- Properties with none-of constraints
- Properties with complex constraints