IEC 62541-6:2020 RLV contains both the official IEC International Standard and its Redline version. The Redline version is not an official document, it is available in English only and provides you with a quick and easy way to compare all the changes between the official IEC Standard and its previous edition.
added JSON encoding for PubSub (non-reversible);
added JSON encoding for Client/Server (reversible);
added support for optional fields in structures;
added support for Unions.
b) Transport mappings:
added WebSocket secure connection WSS;
added support for reverse connectivity;
added support for session-less service invocation in HTTPS.
c) Deprecated Transport (missing support on most platforms):
SOAP/HTTP with WS-SecureConversation (all encodings).
d) Added mapping for JSON Web Token.
e) Added support for Unions to NodeSet Schema.
f) Added batch operations to add/delete nodes to/from NodeSet Schema.
g) Added support for multi-dimensional arrays outside of Variants.
h) Added binary representation for Decimal data types.
i) Added mapping for an OAuth2 Authorization Framework.