Features

This section documents validation and schema keywords supported by YAML Schema and the ys CLI. For the normative keyword set, see the published schema at yaml-schema.yaml.

Topics

• CLI — Command-line usage, instance $schema, JSON errors
• Basics — Empty schemas, boolean schemas, basic types
• Types — Strings (including Unicode length), numbers, arrays, objects, etc.
• String formats — format for dates, times, email, URI, UUID, and custom labels
• Validation — Enums, const, descriptions, shared constraint examples
• Composition — allOf, anyOf, oneOf, not
• Multiple types — type: [string, number] style unions
• Conditionals — dependentRequired, dependentSchemas, if / then / else
• Unevaluated keywords — unevaluatedProperties, unevaluatedItems
• References — $defs, $ref, external resolution, circular refs

Type system

YAML Schema supports these types:

• string — Text values
• number — Numeric values (integers and floats)
• integer — Whole numbers
• boolean — True/false values
• null — Null values
• array — Ordered lists
• object — Key-value mappings

Types combine with validation keywords and composition to describe your YAML documents.

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Table of contents

• Basics
• Types
• String formats
• Validation
• Composition
• Multiple Types
• Conditionals
• Unevaluated keywords
• CLI
• References