Why I need to register general callback prior to registering for tag

I am not sure if I understand why do I need to register general callback (without any tag) prior to registering specific tag subscription callback.

Is it for the purposes of receiving events that does not have a tag? I do not expect such events… :frowning:

I have found this resolution in the forum:

A general callback is a registered function that handles events that the client isn’t specifically waiting for (roughly). Before using request/reply, you must register a general callback.

Ok - but tell me - what to do with events that I do not expect?

There are sometimes system level events that are sent to all clients.