diff --git a/Documentation/sophia-net-signalling.md b/Documentation/sophia-net-signalling.md
index 79cee74..648e0cb 100644
--- a/Documentation/sophia-net-signalling.md
+++ b/Documentation/sophia-net-signalling.md
@@ -10,7 +10,8 @@ the following Signalling applies:
 |0x80		|TBS 6903-X GSE Packets				|
 |0x81		|AC-3 Audio							|
 |0x82		|PID only used for PCR				|
-|0x83       |ULE (RFC 4326)                     |
+|0x83		|AC-3 True HD Audio                 |
+|0x84       |ULE (RFC 4326)                     |
 
 ## Descriptors: