PJM Messages Public Web Service response

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://raw.githubusercontent.com/api-evangelist/pjm/refs/heads/main/json-schema/pjm-message.json",
  "title": "PJM Messages Public Web Service response",
  "description": "Derived by API Evangelist from the verbatim live response of GET https://messages.pjm.com/messages/rest/public/messages (Accept: application/json), captured 2026-07-27 and saved at examples/pjm-messages-public-response.json. PJM publishes no schema for this endpoint; field names, types and null-ability are taken only from the observed payload, so fields that were empty or null in that capture are typed permissively rather than guessed.",
  "x-provenance": {
    "generated": "2026-07-27",
    "method": "derived",
    "source": "examples/pjm-messages-public-response.json",
    "endpoint": "https://messages.pjm.com/messages/rest/public/messages"
  },
  "type": "object",
  "required": ["messages"],
  "properties": {
    "messages": {
      "type": "array",
      "description": "Current PJM tool/website planned-change and impact notices, the same set rendered on https://www.pjm.com/markets-and-operations/etools/upcoming-changes",
      "items": { "$ref": "#/$defs/message" }
    }
  },
  "$defs": {
    "message": {
      "type": "object",
      "properties": {
        "userMessageId": {
          "type": "integer",
          "description": "PJM identifier for the notice."
        },
        "subject": {
          "type": "string",
          "description": "Short title of the notice."
        },
        "message": {
          "type": "string",
          "description": "Notice body as pre-rendered HTML, including inline style attributes."
        },
        "messageRaw": {
          "type": "string",
          "description": "Notice body as authored HTML, without PJM's presentation wrapper."
        },
        "appearanceFlag": {
          "type": "boolean",
          "description": "Whether the notice is currently displayed."
        },
        "blockAccessFlag": {
          "type": "boolean",
          "description": "Whether the notice corresponds to an access-blocking event."
        },
        "effectiveDate": {
          "type": ["integer", "null"],
          "description": "Epoch milliseconds at which the notice becomes effective."
        },
        "terminateDate": {
          "type": ["integer", "null"],
          "description": "Epoch milliseconds at which the notice expires."
        },
        "applications": {
          "type": "array",
          "description": "Human-readable names of the affected PJM tools/applications.",
          "items": { "type": "string" }
        },
        "applicationIds": {
          "type": "array",
          "description": "PJM numeric identifiers of the affected applications, positionally aligned with applications.",
          "items": { "type": "integer" }
        },
        "sortedApplications": {
          "type": "array",
          "description": "The applications list in PJM's display order.",
          "items": { "type": "string" }
        },
        "changeStart": {
          "type": ["integer", "null"],
          "description": "Epoch milliseconds for the start of the change window."
        },
        "changeEnd": {
          "type": ["integer", "null"],
          "description": "Epoch milliseconds for the end of the change window."
        },
        "changeDuration": {
          "type": ["string", "integer", "null"],
          "description": "Duration of impact. Null in the captured response; type left permissive because no populated example was observed."
        },
        "messageActions": {
          "type": "array",
          "description": "Actions required of the reader, e.g. 'No action required/information only', 'Please share within your organization'.",
          "items": { "type": "string" }
        },
        "messageImpacts": {
          "type": "array",
          "description": "Impact descriptors. Empty in the captured response; item type not asserted because no populated example was observed.",
          "items": {}
        }
      }
    }
  }
}