---
title: "Event"
description: "one change of state, written in the same transaction as the change"
section: concepts
address: /concepts/event
contract: 0476e35e6e275db5
---

# Event

one change of state, written in the same transaction as the change

[figure: Event is a fact at follows scope. The drawing shows its fields and the objects that they point at.]

| property | value |
|---|---|
| kind | fact |
| scope | follows |
| key | the flow, the unit and the moment |
| store | log |
| family | kernel |



## Fields


| field | type | required | note |
|---|---|---|---|
| `flow` | [Flow](/concepts/flow) | yes |  |
| `unit` | `id` | yes |  |
| `at` | `time` | yes |  |
| `by` | [Caller](/concepts/caller) | yes |  |
| `plane` | `one of tenant plane \| work plane` | yes |  |
| `from_place` | `text` | no |  |
| `to_place` | `text` | no |  |
| `outcome` | `text` | yes |  |
| `reason` | `text` | no | typed, from the flow's row |
| `run` | `id` | yes |  |
| `correction_of` | `id` | no | an event that corrects an earlier one names it |



## Routes that use it
- [`/v1/act/correct`](/reference/act/correct) returns it