fixup! Update links.md

Signed-off-by: benjamin-j-powell <[email protected]>

links.md

@@ -212,7 +212,7 @@ further, we can allow for a path link between `pipelinerun.queued` to the
         "from": {
           "context_id": "271069a8-fc18-44f1-b38f-9d70a1695819" # context id of the pipelinerun.queued event
         }
-      },
+      }
     ]
   },
   "subject": {

spec.md

@@ -32,6 +32,7 @@ CDEvents is a common specification for Continuous Delivery events.
     - [source (context)](#source-context)
     - [timestamp](#timestamp)
     - [version](#version)
+  - [OPTIONAL Context  Attributes](#optional-context-attributes)
   - [Context example](#context-example)
 - [CDEvent subject](#cdevent-subject)
   - [REQUIRED Subject Attributes](#required-subject-attributes)
@@ -262,6 +263,61 @@ defined in the [vocabulary](#vocabulary):
   - REQUIRED
   - MUST be a non-empty string
 
+### OPTIONAL Context Attributes
+
+#### chain_id
+
+- Type: [`String`][typesystem]
+- Description: Identifier for a chain as defined in the [links spec](links.md).
+
+- Constraints:
+  - A [UUID version 4](https://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_(random))
+
+#### links
+
+- Type: [`List`][typesystem]
+- Description: A list of link objects as defined in the [links spec](links.md).
+
+- Examples:
+    - A path link which is used to indicate a direct connection between two
+      events 
+
+    ```json
+    [
+      {
+        "link_type": "PATH",
+        "from": {
+          "context_id": "271069a8-fc18-44f1-b38f-9d70a1695819"
+        }
+      }
+    ]
+    ```
+    - A relation link where the `context_id` is was some trigger for this event
+
+    ```json
+    [
+      {
+        "link_type": "RELATION",
+        "link_kind": "TRIGGER",
+        "target": {
+          "context_id": "5328c37f-bb7e-4bb7-84ea-9f5f85e4a7ce"
+        }
+      }
+    ]
+    ```
+    - An end link signaling the end of a chain
+
+    ```json
+    [
+      {
+        "link_type": "PATH",
+        "from": {
+          "context_id": "271069a8-fc18-44f1-b38f-9d70a1695819"
+        }
+      }
+    ]
+    ```
+
 ### Context example
 
 This is an example of a full CDEvent context, rendered in JSON format:
@@ -516,4 +572,4 @@ platforms.
 [typesystem]: https://github.com/cloudevents/spec/blob/v1.0.2/cloudevents/spec.md#type-system
 [datacontenttype]: https://github.com/cloudevents/spec/blob/v1.0.2/cloudevents/spec.md#datacontenttype
 [rfc2406]: https://tools.ietf.org/html/rfc2046
-[purl-spec]: https://github.com/package-url/purl-spec/blob/master/PURL-SPECIFICATION.rst
+[purl-spec]: https://github.com/package-url/purl-spec/blob/master/PURL-SPECIFICATION.rst