*`senderId` Integer - The `webContents.id` that sent the message, you can call `event.sender.sendTo(event.senderId, ...)` to reply to the message, see [ipcRenderer.sendTo][ipc-renderer-sendto] for more information. This only applies to messages sent from a different renderer. Messages sent directly from the main process set `event.senderId` to `0`.
*`senderIsMainFrame` boolean (optional) - Whether the message sent via [ipcRenderer.sendTo][ipc-renderer-sendto] was sent by the main frame. This is relevant when `nodeIntegrationInSubFrames` is enabled in the originating `webContents`.