I have never found
Standard listed in any of the mirad of Genre lists we studied. I understand why you are making this personal request, but we do have a limit of how many entries we can add to the list and need to insure that some number of others are in agreement.
If you make any changes with the Edit Song... command dialog box and leave Genre blank, the default that will automatically appear is
Unknown.
Everyone... should we add "Standard" as a Genre selection?