wikipedia-templates

name	wikipedia-templates
description	Create, design, and understand Wikipedia and MediaWiki templates — template syntax, parser functions, magic words, transclusion vs substitution, Lua modules, template types taxonomy, API detection, and maintenance workflows
license	MIT
compatibility	opencode
depends_on	["wikimedia-api-access"]
skill_discovery_hints	[{"keywords":["template","wikitext template","parser function","transclusion","Lua module"]},{"keywords":["#if","#switch","#invoke","TemplateData","infobox template"]}]
last_verified	"2026-06-10T00:00:00.000Z"

⚠️ User-Agent required: The API examples below hit Wikimedia endpoints. All requests must include a descriptive User-Agent header. See the wikimedia-api-access skill for the correct format.

📖 Prerequisites: For general article structure (infoboxes, categories, navboxes), see wikipedia-page-anatomy. For AST-based programmatic manipulation of template wikitext, see wikimedia-wikitext. For bulk template operations (mass replacement, harvesting infoboxes into Wikidata), see pywikibot.

---

SOP: How Templates Work

Templates are reusable wiki pages transcluded via double braces:

{{Template name}}
{{Template name|param1=value1|param2=value2}}

They live in the Template namespace (NS 10). Shortcuts like {{cn}} resolve to Template:Cn.

Transclusion vs. Substitution

Mechanism	Syntax	Behavior	Use Case
Transclusion	{{Template}}	Content included dynamically — edits to the template update every page using it	Infoboxes, navboxes, maintenance tags
Substitution	{{subst:Template}}	Content copied into the page at save time — no link to template afterward	Signatures (~~~~), user talk messages, template documentation
Safe substitution	{{safesubst:Template}}	Works in both transcluded and substituted contexts	Templates that must work correctly when called from other templates

Transclusion (the default) means the template content is not part of the page's raw wikitext. Use action=parse or the REST API /html endpoint to see the fully rendered page. Substitution places the expanded content directly into the page's wikitext — useful for signatures, page moves, and one-time messages.

Template Parameters

Templates accept parameters in two forms:

{{Template
| named_param    = value          ← Named parameter (preferred for clarity)
| positional     = value          ← Or use bare values without names
}}

<!-- Positional parameters: the first unnamed arg is {{{1}}}, second is {{{2}}}, etc. -->
{{Infobox person|Albert Einstein|14 March 1879}}

Inside the template, parameters are accessed as:

{{{1}}}                   ← Positional parameter (required — shows {{{1}}} if omitted)
{{{named_param|default}}} ← Named parameter with default value
{{{1|}}}                  ← Positional parameter that defaults to empty string
{{{named_param}}}         ← Named parameter (required — shows {{{named_param}}} if omitted)
{{{named_param|}}}        ← Named parameter that defaults to empty string

Key rules:

• Named parameters can use spaces, underscores, or mixed case — {{Template|param name=value}} works
• Parameter names are case-insensitive after normalization (underscores → spaces, first letter upper-cased)
• A blank parameter (|param=) is different from an omitted parameter — use {{{param|}}} to default blank to empty
• Trailing whitespace in parameter values is stripped
• Pipe characters inside values must be escaped with {{!}}

Inclusion Control Tags

These tags control what part of a template page gets transcluded:

Tag	Effect
<noinclude>...</noinclude>	Content visible on the template page itself but not transcluded into articles
<includeonly>...</includeonly>	Content hidden on the template page but included when transcluded
<onlyinclude>...</onlyinclude>	Only this content is transcluded; everything else is ignored

Typical use:

<noinclude>{{Documentation}}</noinclude>
<includeonly>[[Category:Navigation templates]]</includeonly>
{{Navbox | name = ...
}}

• <noinclude> wraps documentation, categories for the template page, and interwiki links
• <includeonly> wraps categories that should apply to pages using the template, not the template itself
• <onlyinclude> is for templates whose entire transcluded content is a subset of the page (rare)

Key Design Principles

1. Keep templates simple. Complex logic belongs in Lua modules (see SOP: Lua Modules below).
2. Always provide defaults. Use {{{param|default}}} so the template degrades gracefully.
3. Document your parameters. Use <noinclude> for a /doc page or inline comments.
4. Avoid expensive parser functions. Each {{#if:}}, {{#ifeq:}}, {{#switch:}}, and {{#time:}} counts toward the 500-node limit.
5. Test in a sandbox. Create Template:Templatename/sandbox and Template:Templatename/testcases.

---

SOP: Parser Functions

Parser functions are wiki-text functions that process arguments and return values. They are called with the {{#function:}} syntax.

Conditional Functions

Function	Syntax	Description
#if	`{{#if: {{{param|}}}	then
#ifeq	`{{#ifeq: a	b
#iferror	`{{#iferror: {{#expr:1/0}}	error
#ifexpr	`{{#ifexpr: 1+1=2	yes
#ifexist	`{{#ifexist: Page title	exists
#switch	{{#switch: {{{type|}}} | case1 = value1 | case2 = value2 | #default = fallback}}	Multi-way branch

Common patterns:

{{#if: {{{image|}}}
| [[File:{{{image}}}|thumb]]
| <!-- No image — display nothing -->
}}

{{#switch: {{{type|}}}
| person = {{Infobox person}}
| place  = {{Infobox settlement}}
| book   = {{Infobox book}}
| #default = {{Infobox generic}}
}}

{{#ifeq: {{{url|}}} | {{{archive-url|}}}
| <!-- URL and archive are the same — show one -->
| {{cite web |url={{{url|}}} |archive-url={{{archive-url|}}}
           |archive-date={{{archive-date|}}} }}
}}

Data Functions

Function	Syntax	Description
#expr	{{#expr: 1+1}}	Evaluates a mathematical expression and returns the result
#time	{{#time: Y-m-d}}	Formats a date/time, defaulting to the current UTC time
#timel	{{#timel: Y-m-d}}	Same as #time but in the wiki's local time

Common #time format strings:

Code	Output	Example
Y	4-digit year	2026
y	2-digit year	26
F	Full month name	June
M	Abbreviated month	Jun
m	2-digit month	06
j	Day of month (no leading zero)	8
d	2-digit day of month	08
H	2-digit hour (00–23)	14
i	2-digit minute	30
s	2-digit second	05

Technical Functions

Function	Syntax	Description
#tag	{{#tag: ref | citation text | name=foo}}	Generates an XML-like tag (<ref>...</ref>)
#invoke	`{{#invoke: ModuleName	functionName
#property	{{#property: P18}}	Fetches a Wikidata property for the current page's item
#statements	{{#statements: P18|from=Q123}}	Fetches a Wikidata property for a specific Q-item
#invoke	See SOP: Lua Modules below

String Functions (via #invoke:String)

Common string operations are available through Module:String:

{{#invoke:String|len|S}}         ← Length
{{#invoke:String|sub|S|start|end}}  ← Substring
{{#invoke:String|match|S|pattern}}  ← Regex match
{{#invoke:String|find|S|target}}    ← Find position
{{#invoke:String|replace|S|old|new}} ← Replace
{{#invoke:String|trim|S}}         ← Strip whitespace

Performance Notes

• #if is cheaper than #ifeq (no comparison needed)
• #switch is more efficient than nested #ifeq chains (uses a hash lookup)
• #ifexist is expensive — each call hits the database; limit to ~10 per page
• #expr is slower than a precomputed value
• #time with #time: Y (year only) is cached; complex #time formats are not
• See Limits and Quotas below for hard caps

---

SOP: Magic Words

Magic words are special strings that return wiki metadata or behavior. They are recognized by MediaWiki's parser.

Behavior Switches

These control page behavior and are placed anywhere in the wikitext:

Word	Effect
__NOTOC__	Hides the table of contents
__FORCETOC__	Forces the TOC to appear before the first heading
__TOC__	Places the TOC at this position
__NOEDITSECTION__	Hides edit links next to section headings
__HIDDENCAT__	Hides the category from readers (on category pages)
__EXPECTUNUSEDCATEGORY__	Suppresses "unused category" warnings
__DISAMBIG__	Marks the page as a disambiguation page
__NEWSECTIONLINK__	Adds a "new section" tab on talk pages
__NONEWSECTIONLINK__	Removes the "new section" tab
__NOGALLERY__	Displays file links instead of galleries on category pages
__INDEX__ / __NOINDEX__	Allows or disallows search engine indexing

Variables

Variables return page-specific or wiki-specific data:

Variable	Returns	Example Output
{{PAGENAME}}	Current page title (without namespace)	Albert Einstein
{{PAGENAMEE}}	URL-encoded page name	Albert_Einstein
{{FULLPAGENAME}}	Full page title with namespace	Template:Infobox person
{{FULLPAGENAMEE}}	URL-encoded full title	Template:Infobox_person
{{NAMESPACE}}	Namespace name	Template
{{NAMESPACEE}}	URL-encoded namespace	Template
{{NAMESPACENUMBER}}	Namespace number	10
{{SITENAME}}	Wiki site name	Wikipedia
{{SERVER}}	Wiki domain URL	https://en.wikipedia.org
{{SERVERNAME}}	Wiki domain name	en.wikipedia.org
{{SCRIPTPATH}}	Script path	/w
{{CURRENTYEAR}}	Current year	2026
{{CURRENTMONTH}}	Current month (01–12)	06
{{CURRENTMONTHNAME}}	Current month name	June
{{CURRENTDAY}}	Current day of month	8
{{CURRENTDAYNAME}}	Current day name	Monday
{{CURRENTTIME}}	Current time (HH:mm)	14:30
{{CURRENTTIMESTAMP}}	Current ISO timestamp	20260608143005
{{REVISIONID}}	Current revision ID	123456789
{{REVISIONDAY}}	Day of last revision	8
{{REVISIONMONTH}}	Month of last revision	06
{{REVISIONYEAR}}	Year of last revision	2026
{{REVISIONTIMESTAMP}}	Timestamp of last revision	20260608143005
{{REVISIONUSER}}	User who made the last edit	ExampleUser
{{SITENAME}}	Wiki site name	Wikipedia
{{CONTENTLANGUAGE}}	Wiki content language	en
{{PAGESINCATEGORY:Category name}}	Page count in category	42
{{PAGESIZE:Page title}}	Size of a page in bytes	12345
{{PROTECTIONLEVEL:action}}	Protection level for an action	autoconfirmed, sysop, or empty
{{PROTECTIONEXPIRY:action}}	Protection expiry timestamp	infinity or date

Template-Specific Magic Words

Word	Effect
{{TALKPAGENAME}}	Full talk page title
{{SUBPAGENAME}}	Subpage name (after the last /)
{{REVISIONID}}	Current revision ID (useful in templates for cache busting)

---

SOP: Lua Modules

Some complex templates are backed by Lua modules through the Scribunto extension. Instead of parser function logic in wikitext, the logic lives in a Lua module in the Module: namespace (NS 828).

How to Identify Lua-Backed Templates

Check the template source for {{#invoke:}}:

{{#invoke:Infobox|infobox}}
{{#invoke:Check for unknown parameters|check|unknown={{Main other|_VALUE_{{PAGENAME}}}}}}
{{#invoke:String|replace|source=...|old=...|new=...}}

Common Lua-backed templates include:

• {{Infobox settlement}} — Module:Infobox with Module:Infobox settlement
• {{Cite web}}, {{Cite book}}, etc. — Module:Citation/CS1
• {{sfn}}, {{harvnb}} — Module:Footnotes
• {{Authority control}} — Module:Authority control
• Navigation boxes — Module:Navbox (with Module:Navbox/configuration)

Module Structure

Module:Name/
├── Module:Name               ← Main module code
├── Module:Name/configuration ← Configuration data
├── Module:Name/data          ← Large data tables
└── Module:Name/i18n          ← Internationalization strings

How #invoke Works

{{#invoke:ModuleName|functionName|arg1|arg2|named_param=value}}

The Lua function receives a frame object:

local p = {}

function p.functionName(frame)
    local arg1 = frame.args[1]            -- Positional argument
    local named = frame.args["named_param"] -- Named argument
    local parent = frame:getParent()      -- Caller's arguments
    return "result"
end

return p

Detection via API

action=query&prop=templates&titles=Infobox_settlement&format=json

Look for entries with ns=828 (Module namespace) to identify Lua dependencies.

When to Use a Module vs. Wikitext-Only Template

Situation	Best Approach
Simple parameter display	Wikitext template
Conditional formatting with ≤5 branches	{{#switch}}
Complex data processing, loops, or string manipulation	Lua module
Citation formatting (hundreds of edge cases)	Lua module
Algorithmic logic with conditional branching	Lua module
When template exceeds post-expand include size (2 MB)	Lua module

⚠️ Editing Lua modules requires templateeditor or sysop rights on most wikis. You can view the source, but changes must be suggested on the talk page or made by an authorized editor.

---

SOP: Template Types Taxonomy

Templates on Wikipedia serve many distinct purposes. Here is the taxonomy with examples:

Infoboxes

Right-aligned summary tables presenting key facts:

Template	Purpose	Lua?
{{Infobox person}}	People	No
{{Infobox settlement}}	Cities, towns	Yes
{{Infobox country}}	Sovereign states	No
{{Infobox film}}	Movies	No
{{Infobox company}}	Organizations	No
{{Infobox scientist}}	Researchers	No
{{Infobox book}}	Books	No
{{Infobox military conflict}}	Battles, wars	No

Citation Templates

Inline reference formatting (see wikipedia-citations skill for details):

Template	For
{{cite web}}	Web pages
{{cite news}}	News articles
{{cite book}}	Books
{{cite journal}}	Academic papers
{{sfn}}	Shortened footnote (Lua-backed)
{{harvnb}}	Harvard-style citation

Navigation Templates

Type	Template	Purpose
Navbox	{{Navbox}}	Collapsible navigation at bottom of article
Navbox with collapsible groups	{{Navbox with collapsible groups}}	Multi-section navbox
Sidebar	{{Sidebar}}	Right-aligned navigation column
Series box	{{Sister project links}}	Links to related wiki projects
Authority control	{{Authority control}}	Library catalog identifiers
Portal bar	{{Portal bar}}	Links to related portals

Maintenance Templates

Tags that signal article issues (see wikipedia-page-anatomy for full list):

{{cn}}              {{POV}}
{{dead link}}        {{clarify}}
{{expand section}}   {{stub}}
{{original research}} {{weasel inline}}
{{better source}}    {{failed verification}}

Banners and Assessment

Talk page templates for WikiProject coordination:

{{WikiProject Biography|living=yes|class=B|importance=High}}
{{WikiProject Physics|class=C|importance=Mid}}
{{ArticleHistory}}
{{Annual report}}

Structural Templates

Templates that organize the page itself:

{{About|the physicist}}           ← Hatnote disambiguation
{{For|other uses}}                ← Other uses
{{Distinguish|OtherPerson}}       ← Similar name confusion
{{Redirect|Einstein}}             ← Redirect hatnote
{{TOC left}}                      ← Floating table of contents
{{Clear}}                         ← Clear floating elements
{{-}}                             ← Same as {{clear}}

Media and Linking Templates

{{Commons category}}
{{Wikiquote}}
{{External media}}
{{Superimpose}}                   ← Image overlay
{{Image label}}                   ← Labels on images
{{Listen}}                        ← Audio file player
{{Multiple image}}                ← Gallery layout

Stub Templates

{{stub}}              {{physics-stub}}
{{bio-stub}}          {{film-stub}}
{{geo-stub}}          {{sci-stub}}

---

SOP: Template Detection and API Usage

Find All Templates on a Page

action=query&prop=templates&titles=Albert_Einstein&format=json

Returns all templates transcluded on the page, with namespace (ns=10 for templates, ns=828 for modules):

{
  "query": {
    "pages": {
      "123": {
        "templates": [
          { "ns": 10, "title": "Template:Infobox person" },
          { "ns": 10, "title": "Template:Authority control" },
          { "ns": 10, "title": "Template:Navbox" },
          { "ns": 828, "title": "Module:Infobox" },
          { "ns": 10, "title": "Template:Cn" }
        ]
      }
    }
  }
}

Find All Pages Using a Template

action=query&list=embeddedin&eititle=Template:Infobox_person&format=json

Pagination via eicontinue. Limit with eilimit. Filter by namespace with einamespace.

Expand a Template

action=expandtemplates&text={{Infobox_person|name=Test}}&format=json

Returns the fully expanded wikitext (all templates, parser functions, and magic words resolved). Useful for debugging what a template actually produces.

Get Template Source

action=raw&title=Template:Infobox_person

Returns the raw wikitext of the template page (no transclusion expansion).

Get Rendered Template

Use the REST API:

GET https://en.wikipedia.org/w/rest.php/v1/page/Template:Infobox_person/html

Returns the template page rendered as HTML5 via Parsoid. For templates that produce visible output, this shows what the template looks like.

---

SOP: Template Protection and Limits

Protection Levels

Level	Required Right	Who Can Edit
None	—	Any autoconfirmed user
autoconfirmed	editsemiprotected	Users 4+ days and 10+ edits
templateeditor	templateeditor	Trusted template editors
sysop (full)	editprotected	Administrators

High-use templates (transcluded on 500,000+ pages) are typically protected at templateeditor or sysop level. Check protection:

action=query&prop=info&inprop=protection&titles=Template:Infobox_person&format=json

Template Limits

Limit	Cap	What Happens When Exceeded
Post-expand include size	2,048,000 bytes	Templates beyond the limit are not expanded — raw {{...}} shown
Template argument size	2,048,000 bytes	Same — template call is preserved unexpanded
Expensive parser function calls	500 per page	#ifexist calls beyond 500 produce errors
Nodes in AST	~10,000,000 soft limit	Pages exceeding this may fail to render
Template inclusion depth	40 levels	Deeply nested templates will fail to expand

How to Check Limits

action=parse&page=Albert_Einstein&prop=modules&format=json

Returns the limitreport with current usage vs. limits:

{
  "parse": {
    "limitreport": {
      "pp-expand-depth": "16/40",
      "pp-expand-size": "32450/2048000",
      "expensive-function-count": "2/500"
    }
  }
}

---

SOP: Template Maintenance

Creating a New Template

1. Create the page Template:YourTemplateName
2. Add the template code with parameter defaults
3. Add <noinclude>{{Documentation}}</noinclude> at the end
4. Create Template:YourTemplateName/doc with usage examples
5. Add categories to the doc page (<includeonly>[[Category:Your template category]]</includeonly>)
6. Create Template:YourTemplateName/sandbox for testing
7. Create Template:YourTemplateName/testcases for automated test cases

Template Documentation (Doc Pages)

Every template should have a /doc subpage:

<!-- Template:YourTemplateName/doc -->
{{Documentation subpage}}
<!-- Description goes here -->
This template displays [purpose].

== Usage ==
{{YourTemplateName |param1= |param2= }}

== Example ==
{{YourTemplateName |param1=Hello |param2=World}}

== TemplateData ==
<templatedata>
{
  "description": "Template purpose",
  "params": {
    "param1": {
      "label": "Parameter 1",
      "description": "What this parameter does",
      "type": "string",
      "required": true
    },
    "param2": {
      "label": "Parameter 2",
      "description": "Another parameter",
      "type": "string",
      "required": false
    }
  }
}
</templatedata>

<includeonly>{{Sandbox other||
<!-- Categories below this line -->
[[Category:Your template category]]
}}</includeonly>

Tracking Categories

Templates often use <includeonly> to add pages to maintenance categories:

<includeonly>{{#if:{{{url|}}}|<!-- OK -->|[[Category:Pages with missing URL]]}}</includeonly>

Common tracking categories:

• Category:Pages with missing parameters — required parameter omitted
• Category:Pages using duplicate arguments in template calls — same param used twice
• Category:Pages with template errors — template fails to render
• Category:Wikipedia template protection — protected templates

Testing Templates

• Sandbox: Template:Name/sandbox — experimental changes without affecting production
• Test cases: Template:Name/testcases — parameter combinations with expected output
• What links here: Special:WhatLinksHere/Template:Name — pages using the template
• Transclusion count: Special:PageInfo/Template:Name — shows usage count
• TemplateData: Structured parameter documentation used by the Visual Editor

---

Tooling

This skill includes helper scripts, reference docs, and templates:

🔧 Expand Template (scripts/expand-template.sh)

Expand a template with parameters via the Action API, showing the fully rendered wikitext:

# Expand a simple template call
./scripts/expand-template.sh "Infobox_person" "name=Albert Einstein|birth_date=14 March 1879"

# Read template call from stdin
echo "{{Infobox_person|name=Test}}" | ./scripts/expand-template.sh -

🔧 Template Usage Lookup (scripts/template-usage.sh)

Find all pages using a template, with count and pagination:

# Show all pages using Template:Cn
./scripts/template-usage.sh "Cn"

# Show with namespaces and total count
./scripts/template-usage.sh "Infobox person" --count

# Limit results
./scripts/template-usage.sh "Stub" --limit 20

🔧 Inspect Template (scripts/inspect-template.sh)

Get comprehensive information about a template: source, protection, Lua dependencies, transclusion count, and tracking categories:

# Full inspection
./scripts/inspect-template.sh "Infobox person"

# Just check protection level
./scripts/inspect-template.sh "Infobox person" --protection

# Show source code only
./scripts/inspect-template.sh "Cite web" --source

📚 Parser Functions Reference (references/parser-functions.md)

Complete reference covering all parser functions with examples, performance notes, and common pitfalls.

📚 Magic Words Reference (references/magic-words.md)

Complete catalog of all magic words organized by category (behavior switches, variables, template-specific).

📚 Template Types Reference (references/template-types.md)

Full taxonomy of template types with examples, usage patterns, and Lua-backing information.

🐍 Template Inspector (assets/template-inspector.py)

Python script that fetches and analyzes a template's structure:

# Full analysis
python3 assets/template-inspector.py "Infobox person"

# Get parameters only
python3 assets/template-inspector.py "Infobox person" --parameters

# Show Lua module dependencies
python3 assets/template-inspector.py "Infobox settlement" --modules

# JSON output for programmatic use
python3 assets/template-inspector.py "Cite web" --format json

🐍 Template Scanner (assets/template-scanner.py)

Python script that scans a page for all template usage, classifying each template by type:

# Scan a Wikipedia article
python3 assets/template-scanner.py "Albert Einstein"

# Group by template type (infobox, citation, navbox, maintenance, etc.)
python3 assets/template-scanner.py "Berlin" --by-type

# Output as JSON
python3 assets/template-scanner.py "Python (programming language)" --format json

# Show Lua module usage
python3 assets/template-scanner.py "Berlin" --modules

---

Cross-References

Related Skill	Why
wikimedia-api-access	User-Agent and API patterns for template detection
wikipedia-page-anatomy	Article structure — where templates appear (infoboxes, navboxes, citations)
wikimedia-wikitext	AST-based template parsing with mwparserfromhell
wikipedia-citations	Citation templates — the most common template type on Wikipedia
wikipedia-talk-page	WikiProject banners on talk pages are templates
wikipedia-wikitables	Table templates and wikitable generation
pywikibot	Bulk template operations (mass replacement, infobox harvesting)