YAML

YAML is a human-oriented data serialization language. Markdown commonly uses a YAML mapping between --- delimiters as frontmatter.

YAML mappings become key-value structures, sequences become arrays, and scalar values can represent strings, numbers, booleans, or null values. Those distinctions matter when frontmatter is queried or validated: the string "true" is not the same value as the boolean true.

md-utils parses frontmatter as structured data and can emit it as either YAML or JSON. Use yq when a workflow should continue working with YAML syntax and formatting.