schema.md

<!--// Auto-generated schema documentation, 2025-07-30 //-->

# MegaWika 2.0 Data Schema


MegaWika 2 is structured as a collection of JSON-lines "chunk" files
organized by Wikipedia language.  Each chunk file contains a collection
of Article objects, one (JSON-encoded) Article per line.  What follows is
documentation for each type in the schema, starting with Article.


## Article

### Fields

- **title** (string): Article title
  - Ex: `"Les Hauts de Hurlevent est l'unique roman d'Emily Brontë ..."`
- **wikicode** (string): Wikimedia source code for article
  - Ex: `"<div id=\"mp_header\" class=\"mp_outerbox\"> ..."`
- **hash** (string): Hash of title and content
  - Ex: `"2c0c3bfb0493fb8ddd5661..."`
- **last\_revision** (string): Datetime of last revision
  - Ex: `"2023-12-03T10:50:40Z"`
- **first\_revision** (string | null): Datetime of initial article creation, if it could be retrieved.
  - Ex: `"2023-09-04T08:19:40Z"`
- **first\_revision\_access\_date** (string | null): Datetime first revision was retrieved from Wikipedia Action API
  - Ex: `"2023-12-03T10:55:40Z"`
- **cross\_lingual\_links** (object[string, string] | null): A dictionary mapping this article onto articles on the same topic in other languages; keys represent language codes, values represent the title of the article in that language.
  - Ex: `{"en": "Wuthering Heights", "es": "Cumbres Borrascosas"}`
- **cross\_lingual\_links\_access\_date** (string | null): Datetime cross-lingual links were retrieved from Wikipedia Action API
  - Ex: `"2023-12-03T10:56:40Z"`
- **text** (string): Natural-language text of article
  - Ex: `"Les Hauts de Hurlevent est l'unique roman d'Emily Brontë ..."`
- **elements** (array[[Heading](#heading) | [Table](#table) | [Infobox](#infobox) | [Paragraph](#paragraph) | [Math](#math) | [Code](#code) | [Preformatted](#preformatted)]): Article structure: paragraphs, text and citation elements, etc.
- **excerpts\_with\_citations** (array[[ExcerptWithCitations](#excerptwithcitations)]): A list of all citations from the article and the associated text excerpts they appear in.  This data is a postprocessed subset of the data in the elements list and is provided for convenience.


## Citation

### Fields

- **content** (string): Citation content
  - Ex: `"<ref>{{Citation |last=Thomas |first=Darcy |year=2013 ..."`
- **char\_index** (integer): Character index of this citation in the enclosing sentence or excerpt
  - Ex: `39`
- **name** (string | null): Optional citation name
  - Ex: `null`
  - Ex: `"Thomas2013"`
- **url** (string | null): Extracted URL, if web citation
  - Ex: `"https://example.com/emily-bronte/..."`
- **source\_text** (string | null): Extracted source text, if source download and extraction succeeded
  - Ex: `"Emily Brontë avait deux sœurs ..."`
- **source\_code\_content\_type** (string | null): Downloaded source code content type, if download succeeded and content-type header was received
  - Ex: `"text/html"`
  - Ex: `"text/html; charset=ISO-8859-1"`
- **source\_code\_num\_bytes** (integer | null): Not used
  - Ex: `null`
- **source\_code\_num\_chars** (integer | null): Size of downloaded source code in characters, if source download succeeded and code can be decoded as text
  - Ex: `100000`
- **source\_download\_date** (string | null): Datetime source code was downloaded from the web
  - Ex: `"2023-12-03T10:50:40Z"`
- **source\_download\_error** (string | null): Source download error message, if there was an error
  - Ex: `null`
  - Ex: `"Download is too large (2.4 MB)"`
  - Ex: `"ConnectTimeoutError: ..."`
- **source\_extract\_error** (string | null): Source extraction error message, if there was an error
  - Ex: `null`
  - Ex: `"Text is too short (50 words)"`
  - Ex: `"Exception: ..."`
- **source\_snippet** (string | null): A relevant snippet from the source document, excertped manually by Wikipedia editor; stored in the `quote` field of the relevant citation templates.
  - Ex: `"Emily Brontë avait deux sœurs"`
- **source\_quality\_label** (integer | null): An integer between 1 and 5 representing the predicted relevance and quality of the text extracted from the source page: 1 is irrelevant content like 404 text and paywalls, 2 is likely irrelevant or unreadable content like a list of headlines or mangled table, 3 is potentially relevant content like a book abstract, 4 is likely relevant content but with some quality issues, and 5 is relevant content that is well-formatted.
  - Ex: `4`
- **source\_quality\_raw\_score** (number | null): The raw score output by the source quality regression model, generally between 0 and 1.  The source quality label is computed from the raw score and has a monotonic but non-linear relationship.
  - Ex: `0.8`

### Example JSON

```json
{
  "content": "<ref>{{Citation |last=Thomas |first=Darcy |year=2013 ...",
  "char_index": 39,
  "name": null,
  "url": "https://example.com/emily-bronte/...",
  "source_text": "Emily Brontë avait deux sœurs ...",
  "source_code_content_type": "text/html",
  "source_code_num_bytes": null,
  "source_code_num_chars": 100000,
  "source_download_date": "2023-12-03T10:50:40Z",
  "source_download_error": null,
  "source_extract_error": null,
  "source_snippet": "Emily Brontë avait deux sœurs",
  "source_quality_label": 4,
  "source_quality_raw_score": 0.8
}
```


## CitationNeeded

### Fields

- **type** (const string = `"citation-needed"`): Used to differentiate from other element types
- **content** (string): Citation-needed element content
  - Ex: `"{{Citation needed|date=September 2015}}"`
- **char\_index** (integer): Character index of this citation-needed in the enclosing sentence or excerpt
  - Ex: `39`

### Example JSON

```json
{
  "type": "citation-needed",
  "content": "{{Citation needed|date=September 2015}}",
  "char_index": 39
}
```


## Code

### Fields

- **type** (const string = `"code"`): Used to differentiate from other element types
- **language** (string | null): Code language (as used for syntax highlighting)
  - Ex: `"cpp"`
- **content** (string): Code block content
  - Ex: `"int main() { ..."`

### Example JSON

```json
{
  "type": "code",
  "language": "cpp",
  "content": "int main() { ..."
}
```


## ExcerptWithCitations

### Fields

- **text** (string): The text of three consecutive sentences from an article
  - Ex: `"Les Hauts de Hurlevent est .... défis à la culture victorienne."`
- **translated\_text** (string | null): English translation of the excerpt text, if not in English Wikipedia
  - Ex: `"Wuthering Heights is .... challenges to Victorian culture."`
- **citations** (array[[Citation](#citation)]): Citation(s) appearing in the final sentence of this excerpt


## Heading

### Fields

- **type** (const string = `"heading"`): Used to differentiate from other element types
- **text** (string): Heading text
  - Ex: `"Personnages"`
- **translated\_text** (string | null): English translation of heading text, if not in English Wikipedia
  - Ex: `"Characters"`
- **level** (integer): Heading level (1 being top-level/most general, 6 being bottom-level/most specific)
  - Ex: `2`
- **citations** (array[[Citation](#citation)]): Citations appearing in this heading
- **citations\_needed** (array[[CitationNeeded](#citationneeded)]): Citation-needed elements appearing in this heading


## Infobox

### Fields

- **type** (const string = `"infobox"`): Used to differentiate from other element types
- **content** (string): Infobox content
  - Ex: `"{{Infobox Livre\n| auteur = Emily Brontë\n...\n}"`

### Example JSON

```json
{
  "type": "infobox",
  "content": "{{Infobox Livre\n| auteur = Emily Brontë\n...\n}"
}
```


## Math

### Fields

- **type** (const string = `"math"`): Used to differentiate from other element types
- **content** (string): Math block content
  - Ex: `"\\sin 2\\pi x + \\ln e ..."`

### Example JSON

```json
{
  "type": "math",
  "content": "\\sin 2\\pi x + \\ln e ..."
}
```


## Paragraph

### Fields

- **type** (const string = `"paragraph"`): Used to differentiate from other element types
- **sentences** (array[[Sentence](#sentence)]): List of sentences in this paragraph


## Preformatted

### Fields

- **type** (const string = `"preformatted"`): Used to differentiate from other element types
- **content** (string): Preformatted block content
  - Ex: `"____\n|DD|____T_\n|_ |_____|<\n  @-@-@-oo\\\n"`

### Example JSON

```json
{
  "type": "preformatted",
  "content": "____\n|DD|____T_\n|_ |_____|<\n  @-@-@-oo\\\n"
}
```


## Sentence

### Fields

- **text** (string): Sentence text content
  - Ex: `"Les Hauts de Hurlevent est l'unique roman d'Emily Brontë."`
- **translated\_text** (string | null): English translation of sentence text content, if not in English Wikipedia
  - Ex: `"Wuthering Heights is the only novel by Emily Brontë."`
- **trailing\_whitespace** (string): If the sentence was originally followed by whitespace, this will be a space. If the sentence was not followed by whitespace (for example, if it was followed by a quotation mark), this will be the empty string.
  - Ex: `" "`
  - Ex: `""`
- **citations** (array[[Citation](#citation)]): Citations appearing in this sentence
- **citations\_needed** (array[[CitationNeeded](#citationneeded)]): Citation-needed elements appearing in this sentence


## Table

### Fields

- **type** (const string = `"table"`): Used to differentiate from other element types
- **content** (string): Table content
  - Ex: `"{| class=\"wikitable\"\n|+ Personnages\n|-\n! Nom !! ...\n...\n|}"`

### Example JSON

```json
{
  "type": "table",
  "content": "{| class=\"wikitable\"\n|+ Personnages\n|-\n! Nom !! ...\n...\n|}"
}
```