diff --git a/docs/api/messages.md b/docs/api/messages.md
index 463cc1a..e85e548 100644
--- a/docs/api/messages.md
+++ b/docs/api/messages.md
@@ -66,4 +66,22 @@ Heartbeat messages are posted to the heartbeat channel periodically.
 | Field     | Datatype | Description                          |
 | --------- | -------- | ------------------------------------ |
 | new_block | int      | The current block number             |
-| old_block | int      | Last block number that was received. |
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+| old_block | int      | Last block number that was received. |
+
+### TableDelta
+
+| Field          | Datatype        | Description       |
+| -------------- | --------------- | ----------------- |
+| blocknum       | int             | Block number      |
+| blocktimestamp | time            | Block timestamp   |
+| name           | string          | Table name        |
+| rows           | TableDeltaRow[] | Rows in the delta |
+
+
+### TableDeltaRow
+
+| Field    | Datatype      | Description                       |
+| -------- | ------------- | --------------------------------- |
+| present  | bool          | -                                 |
+| data     | any           | Decoded data                      |
+| raw_data | base64_string | Raw data in base64 encoded string |
\ No newline at end of file