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+# Deprecation and Sunset extension
+
+This specification defines attributes that can be included in CloudEvents to
+indicate to [consumers](../spec.md#consumer) or
+[intermediaries](../spec.md#intermediary) the deprecation and sunset status of
+the event type. These attributes inform consumers of CloudEvents about upcoming
+changes or removals, facilitating smoother transitions and proactive
+adjustments.
+
+## Notational Conventions
+
+As with the main [CloudEvents specification](../spec.md), the key words "MUST",
+"MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
+"RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as
+described in [RFC 2119](https://tools.ietf.org/html/rfc2119).
+
+However, the scope of these key words is limited to when this extension is
+used. For example, an attribute being marked as "REQUIRED" does not mean it
+needs to be in all CloudEvents, rather it needs to be included only when this
+extension is being used.
+
+## Attributes
+
+### deprecation
+
+- Type: `String`
+- Description: Indicates that the event type is deprecated. This can be a
+  boolean `true` or a date in [RFC 5322](https://tools.ietf.org/html/rfc5322)
+  format indicating when the deprecation was announced.
+- Constraints
+  - REQUIRED
+  - If the value is a date, it MUST be formatted according to RFC 5322.
+- Examples:
+  - A boolean deprecation: `"deprecation": "true"`
+  - A date-based deprecation: `"deprecation": "Sun, 11 Aug 2024 23:59:59 GMT"`
+
+### sunset
+
+- Type: `String`
+- Description: Specifies the future date and time when the event type will
+  become unsupported, formatted according to
+  [RFC 8594](https://tools.ietf.org/html/rfc8594).
+- Constraints
+  - OPTIONAL
+  - The timestamp MUST be later or the same as the one given in the
+    `deprecation` field.
+- Example: `"sunset": "Wed, 14 Aug 2024 23:59:59 GMT"`
+
+## Usage
+
+When this extension is used, producers MUST set the value of the `deprecation`
+attribute to `true` or the `timestamp` of when an event is being phased out but
+still supported. This gives consumers a heads-up that they should begin
+migrating to a new event type or version.
+
+The `sunset` attribute SHOULD specify the exact date and time when the event
+will no longer be supported. This is the final cutoff date after which the
+event will no longer function as expected.