Note

The FreeCAD website uses the yaml format for its configuration, front matter and examples, as it is easier to read than toml or json. Converters from YAML to TOML or JSON and vice-versa are available online if necessary.

What is a front matter?

Content pages can store custom metadata to enhance their semantics. In most Static Site Generator like Hugo, this is achieved via the front matter fields. The front matter is defined at the top of every content text file such as Markdown in between tags, e.g. --- for YAML.

By default, a title front matter field must be provided for each page. Additionally, many more fields can be specified. Field values can be rather minimal, such as a single string, number, boolean, but can also contain lists (also called slices), maps (also called dictionaries), or even a combination of different nested types.

Front matter fields and values

TODO…

Note

For all Hugo methods, functions, and default fields, the CamelCase formatting is used.

For all custom Trigo theme naming and fields, snake_case formatting is used instead to help distinguish from official Hugo syntax. CSS classes and IDs use hyphens like custom-class.

YAML syntax

Case	Example	Quote?	Comment
Simple string	title: My Blog	❌ No	Safe plain string
String with colon + space	title: "YAML: The Guide"	✅ Yes	Key confusion (YAML: )
String with #	description: "C# basics"	✅ Yes	# starts comment
String starting with *	alias: "*draft"	✅ Yes	* is YAML alias marker
String starting with &	key: "&value"	✅ Yes	& is YAML anchor
URL	baseURL: https://example.com	❌ No	Safe URL (: not followed by space)
URL with fragment	url: "https://example.com/page#intro"	✅ Yes	# starts comment
Number	paginate: 10	❌ No	Proper numeric type
Leading zero	id: "00123"	✅ Yes	Numeric parsing (leading zeros removed)
Date	date: 2026-03-03	❌ No	Proper date object
Null value	field: null	❌ No	Proper null
Boolean	draft: true	❌ No	Proper boolean
Boolean-like word	title: "On"	✅ Yes	on is YAML boolean
Multiline text	summary: |	❌ No	> is folded and | is literal block scalars
Inline array	tags: [hugo, blog]	❌ No	Safe inline list
Block array	- hugo	❌ No	Safe block list (more readable than inline)

Hugo-Specific Cases

Case	Example	Quote?	Comment
Simple glob pattern	include: "*.md"	✅ Yes	* is wildcard
Recursive glob pattern	exclude: "**/*.draft.md"	✅ Yes	** is super wildcard
Glob slice	matrix: ["! en", "v1.*.*", "{fr, de}"]	✅ Yes	Negation, single, list and range

See Hugo Glob patterns docs.

Sveltia CMS config

Case	Example	Quote?	Comment
Simple string	label: Blog	❌ No	Plain string is safe
Folder path	folder: content/blog	❌ No	No special YAML chars
Boolean field option	required: true	❌ No	Must remain boolean
Boolean mistakenly quoted	required: "true"	❌ No	Becomes string → breaks validation
Number field option	max: 10	❌ No	Must remain numeric
String that looks boolean	default: "on"	✅ Yes	on becomes boolean otherwise
Glob pattern	pattern: "*.md"	✅ Yes	* is YAML alias symbol
Recursive glob	exclude: "**/*.draft.md"	✅ Yes	* must be quoted
Regex pattern	pattern: "^[a-z0-9-]+$"	✅ Yes	Contains [], ^, $, etc.
Template variables	slug: "{{slug}}"	✅ Yes	{} should be quoted
Preview path template	preview_path: "blog/{{slug}}"	✅ Yes	Prevent parsing issues
Value containing #	default: "C#"	✅ Yes	# starts comment
Option list (normal)	- draft	❌ No	Safe string
Option list (boolean-like)	- "on"	✅ Yes	Prevent boolean coercion
Datetime default	default: 2026-03-03	❌ No	Keeps date type
Datetime wrongly quoted	default: "2026-03-03"	⚠️ Avoid	Becomes string, may break widget

See Sveltia CMS docs.