While you're at it, there are two places in Part 6 that mention a minimum buffer or chunk size of 8196.

Just search '8196' and you'll find them.

I remember the BSI also raised a question if 8192 is the "correct" value here.
Randy pointed out that changing this value creates a potential incompatibility.
Therefore the current stack implements this check exactly as it was written in
the spec. That means Send/ReceiveBufferSize must be > 8192 and we fail to
connect if Send/ReceiveBufferSize is <= 8192.

See section 6.7.1 and 6.7.2. to make sure they are consistent with the fix (table 36).

Does anybody know what the resolution to this will be? Will the specification change and an errata be issued, or will the current definition stand?

BSI complained about two different numbers

Table 35 – OPC UA TCP Hello Message
ReceiveBufferSize and SendBufferSize
This value shall be greater than 8 192 bytes.

Table 36 – OPC UA TCP Acknowledge Message
ReceiveBufferSize and SendBufferSize
This value shall be greater than 8 192 bytes.

6.7 OPC UA Secure Conversation
UASC requires a TransportProtocol buffer size that is at least 8196 bytes.

6.7.2 MessageChunk structure
The MessageChunkSize depends on the transport protocol but shall be at least 8196 bytes.

The official answer was:
8196 is correct because of 4 bytes used for message size

Not sure where this statement is coming from.
Table 34 – OPC UA TCP Message header
MessageSize
The length of the Message, in bytes. This value includes the 8 bytes for the Message header.

I would expect that both numbers should be the same.

From a logical point of view, a min message size of 8KByte = 8192Byte makes sense. Therefore >= 8192 would be the logical definition.

Several implementations use >= 8192.
Changing such implementations to force > 8192 creates more interoperability issues. I think this is a bad idea and this was not requested by the BSI. They just asked for clarification why there are two different numbers.

Remove the limits from the OPC UA TCP description.
Change the limit to >= 8192 for OPC UA Secure Conversation.

Reviewed and accepted changes edited in the meeting in DRAFT 1.04.02 and the 1.03 Errata.