diff --git a/MessagingClient.markdown b/MessagingClient.markdown
index d52c1df..536e400 100644
--- a/MessagingClient.markdown
+++ b/MessagingClient.markdown
@@ -9,7 +9,7 @@ The client uses a single channel for all messages. The [channel descriptor](BSP#
 
 ### Message types
 
-**0: PRIVATE_MESSAGE** - The content is a BDF list with three elements: `parent_id` (raw or null), `body` (string), and `attachments` (dictionary or null). `parent_id` is the identifier of a private message to which this is a response. Each key in `attachments` is the name of an attachment, and the value is a list with two elements: `mime_type` (string) and `message_id` (raw).
+**0: PRIVATE_MESSAGE** - The content is a list with four elements: `parent_id` (raw or null), `subject` (string), `body` (string), and `attachments` (dictionary or null). `parent_id` is the identifier of a private message to which this is a response. Each key in `attachments` is the name of an attachment, and the value is a list with two elements: `mime_type` (string) and `message_id` (raw).
 
 **1: ATTACHMENT** - The content is raw data.