OK, point taken
But I still would like to be able to see than data in the Extended Tags field
And another big request would be to make it possible for Mp3tag to also change that data: /t/19764/1
So for now I wish I would see that parameter in there even if it would remain non-editable; and in the future if that kind of data would become editable in Mp3tag, your point would no longer be the explanation of why this data cannot be shown there