{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://concert.foundation/signet/v0.1/event.schema.json",
  "title": "Event",
  "description": "An append-only record of a material change. Tamper-evident via hash chaining.",
  "type": "object",
  "required": [
    "id",
    "eventType",
    "subject",
    "actor",
    "timestamp",
    "provenance"
  ],
  "additionalProperties": false,
  "properties": {
    "@context": {
      "type": [
        "string",
        "object",
        "array"
      ]
    },
    "type": {
      "const": "Event"
    },
    "id": {
      "$ref": "definitions.schema.json#/definitions/Identifier"
    },
    "eventType": {
      "type": "string",
      "description": "See codelists/eventType.csv (open)."
    },
    "subject": {
      "$ref": "definitions.schema.json#/definitions/Identifier"
    },
    "actor": {
      "$ref": "definitions.schema.json#/definitions/Identifier"
    },
    "timestamp": {
      "type": "string",
      "format": "date-time"
    },
    "payload": {
      "type": "object"
    },
    "previousEventHash": {
      "type": "string",
      "description": "Hash of the prior event, forming a tamper-evident chain."
    },
    "provenance": {
      "$ref": "definitions.schema.json#/definitions/Provenance"
    }
  }
}