See https://reference.opcfoundation.org/Core/Part6/v105/docs/5.4.1

The CompactEncoding and VerboseEncoding replace the ReversibleEncoding and NonReversibleEncoding. The differences are described in Annex H. The VerboseEncoding also supports the RawData mode defined in OPC 10000-14. In RawData mode, encoders shall omit the following fields:

https://reference.opcfoundation.org/Core/Part6/v105/docs/H

This version of the specification introduced significant optimizations to the JSON encoding, however, there are existing products that support the deprecated JSON encoding. This Annex summarizes the differences and explains how a product can be designed to seamlessly support the deprecated and current versions of the JSON encoding.

The ReversibleEncoding is largely the same as the CompactEncoding. The NonReversibleEncoding is largely the same as the to the VerboseEncoding. The differences are described in the rest of this Annex.

Any product that supports the OpenAPI mappings defined in G.3 only supports the CompactEncoding. The deprecated encodings published earlier versions of this specification are only used by older products implementing MQTT mapping for PubSub defined in OPC 10000-14.

The expectation is all encoders used for Publishers support all four encodings and all decoders for Subscribers support the ReversibleEncoding, CompactEncoding and VerboseEncodings.

Note: it was changed because we got feedback that IT vendors found the old encoding too hard too work with because of the way their systems worked.

We knew it would be a challenge and spent months discussing it in the WG.

Agreed to no change required in Virtual F2F.