EDIT

There is no real need for the ExternalLink.type attribute as today browsers all know how to open e.g. pdf. This was a reason times ago to have a switch between html based protologues and file base protologues for display in dataportal.

In future we may think about internally storing MimeType instead as we do for MediaRepresentation. Or we may even diskuss to merge ExternalLink and MediaRepresentation class. See also #9067.

For now I make this a TaxEditor ticket as it should be removed in TaxEditor primarily to improve UI layout. Once this is done we can make it a model ticket.