the value is not one of the defined possible values
the value is out of the range (integer with min/max, ...)
What should be the behaviour? Discard the message? Return an error? Use a default value?
How to manage possible extensions? Should we reserve some values?
This is required to achieve proper backward compatibility.
Examples:
What should be the behaviour? Discard the message? Return an error? Use a default value? How to manage possible extensions? Should we reserve some values? This is required to achieve proper backward compatibility.