All OPC Event Payload classes contain a string ErrorId field. This field is empty for successes, and non-empty for errors.

The OPC Event Payload classes contain no more information about the error (such as the error message), due to possible negative effect on the payload size, memory consumption, and performance. If your application needs extra information such as the error message strings, derive your payload from one of the OPC Event Payload classes and extend it, or use your own even payload structure.

Each OPC Event Payload class contains a method (called FromXXXX) that creates it from a non-payload object that comes natively from the OPC observable, and a corresponding implicit conversion operator.

For easy viewing, logging and similar purposes, all OPC Event Payload classes contain a ToString() method that formats the contents of relevant fields of the payload into a readable string.