{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "$id": "http://product-information-graph.org/schema/2026-01-12/jsonld/Entity.json",
    "title": "PIG Entity JSON-LD Schema",
    "description": "Validates <strong>Entity</strong> class definitions for individual information objects. Configures which properties (pig:eligibleProperty) and which outgoing links are allowed (pig:eligibleTargetLink). Entities classify primary information objects such as Requirements, Components and Diagrams in a systems engineering context. Supports specialization hierarchies via pig:specializes and optional visual representation via pig:icon.",
    "type": "object",
    "properties": {
        "@id": {
            "$ref": "#/$defs/idString"
        },
        "@type": {
            "$ref": "#/$defs/idString"
        },
        "pig:specializes": {
            "$ref": "#/$defs/idObject"
        },
        "pig:itemType": {
            "type": "object",
            "required": [ "@id" ],
            "properties": {
                "@id": {
                    "type": "string",
                    "enum": [ "pig:Entity" ],
                    "description": "The PigItemType for pig:Entity"
                }
            },
            "additionalProperties": false
        },
        "dcterms:title": {
            "type": "array",
            "minItems": 1,
            "items": {
                "$ref": "#/$defs/languageValue"
            }
        },
        "dcterms:description": {
            "type": "array",
            "items": {
                "$ref": "#/$defs/languageValue"
            }
        },
        "pig:eligibleProperty": {
            "type": "array",
            "description": "Array of Property class references that can be used with this Entity",
            "items": {
                "$ref": "#/$defs/idObject"
            }
        },
        "pig:eligibleTargetLink": {
            "type": "array",
            "description": "Array of Link class references that can be used as outgoing links from this Entity",
            "items": {
                "$ref": "#/$defs/idObject"
            }
        },
        "pig:icon": {
            "type": "object",
            "description": "Optional icon representation for this Entity type",
            "properties": {
                "@value": {
                    "type": "string",
                    "description": "Icon identifier or path"
                }
            },
            "additionalProperties": false
        }
    },
    "required": [
        "@id",
        "pig:itemType",
        "dcterms:title"
    ],
    "oneOf": [
        {
            "required": [ "@type" ],
            "description": "New Entity class (not specialized)"
        },
        {
            "required": [ "pig:specializes" ],
            "description": "Specialized Entity class"
        }
    ],
    "additionalProperties": false,
    "$defs": {
        "idString": {
            "type": "string",
            "pattern": "^(?:[A-Za-z0-9_\\-]+:[^:\\s]+|https?:\\/\\/[^\\s]+)$",
            "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",
                    "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"
        }
    }
}