{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "http://product-information-graph.org/schema/2026-05-08/jsonld/Link.json",
  "title": "CASCaRA Link Schema for JSON-LD",
  "description": "Validates Link class definitions that specify navigable connections between items. Defines enumerated endpoint classes (cas:enumeratedEndpoint) which determine which Entity or Relationship classes can be connected via this link type. Links enable traversal of the information graph and support bi-directional relationships when paired (e.g., 'contains' / 'is contained by').",
  "type": "object",
  "properties": {
    "@id": {
      "$ref": "#/$defs/idString"
    },
    "@type": {
      "type": "string",
      "enum": [ "owl:ObjectProperty" ]
    },
    "cas:specializes": {
      "$ref": "#/$defs/idObject"
    },
    "cas:itemType": {
      "type": "object",
      "required": [ "@id" ],
      "properties": {
        "@id": {
          "type": "string",
          "enum": [ "cas:Link" ],
          "description": "The CASCaRA metamodel item type for cas:Link"
        }
      },
      "additionalProperties": false
    },
    "cas:revision": {
      "type": "string",
      "description": "Revision identifier for version control"
    },
    "cas:priorRevision": {
      "type": "array",
      "description": "Array of prior revision identifiers",
      "maxItems": 2,
      "items": {
        "type": "string"
      }
    },
    "dcterms:modified": {
      "type": "string",
      "format": "date-time",
      "description": "ISO 8601 timestamp of last modification"
    },
    "dcterms:creator": {
      "type": "string",
      "description": "Creator/author of this relationship instance"
    },
    "dcterms:title": {
      "type": "array",
      "minItems": 1,
      "items": {
        "$ref": "#/$defs/languageValue"
      }
    },
    "dcterms:description": {
      "type": "array",
      "minItems": 1,
      "items": {
        "$ref": "#/$defs/languageValue"
      }
    },
    "skos:definition": {
      "type": "array",
      "minItems": 1,
      "items": {
        "$ref": "#/$defs/languageValue"
      }
    },
    "cas:enumeratedEndpoint": {
      "type": "array",
      "minItems": 1,
      "description": "Array of Entity or Relationship class references that can be endpoints for this link",
      "items": {
        "$ref": "#/$defs/idObject"
      }
    },
    "sh:minCount": {
      "type": "integer",
      "minimum": 0
    },
    "sh:maxCount": {
      "type": "integer",
      "minimum": 1
    }
  },
  "required": [
    "@id",
    "@type",
    "cas:itemType",
    "dcterms:title",
    "cas:enumeratedEndpoint"
  ],
  "additionalProperties": false,
  "$defs": {
    "idString": {
      "type": "string",
      "pattern": "^(?:[A-Za-z_][A-Za-z0-9_-]*:[^:\\s]+|https?://[^\\s]+)$",
      "description": "A valid ID string: either a namespaced identifier (prefix:name) or a URL"
    },
    "idObject": {
      "type": "object",
      "required": [ "@id" ],
      "properties": {
        "@id": {
          "$ref": "#/$defs/idString"
        }
      },
      "additionalProperties": false,
      "description": "JSON-LD ID object wrapper"
    },
    "languageValue": {
      "type": "object",
      "required": [ "@value" ],
      "properties": {
        "@value": {
          "type": "string",
          "minLength": 1,
          "description": "The actual text content"
        },
        "@language": {
          "type": "string",
          "pattern": "^[a-z]{2}(-[A-Z]{2})?$",
          "description": "IETF language tag (e.g., 'en', 'de', 'en-US')"
        }
      },
      "additionalProperties": false,
      "description": "Multi-language text value with optional language tag"
    }
  }
}