DisplayUnitFormat GetDefaultProjectUnitFormat( 
   UnitFormatType defaultFormatType
)

{
  // Note: Must be on the QueuedTask.Run()
  var unit_formats = Enum.GetValues(typeof(UnitFormatType))
                      .OfType<UnitFormatType>().ToList();
  System.Diagnostics.Debug.WriteLine("Default project units\r\n");

  foreach (var unit_format in unit_formats)
  {
    var default_unit = DisplayUnitFormats.Instance.GetDefaultProjectUnitFormat(unit_format);
    var line = $"{unit_format}: {default_unit.DisplayName}, {default_unit.UnitCode}";
    System.Diagnostics.Debug.WriteLine(line);
  }
  System.Diagnostics.Debug.WriteLine("");
}

{
  // Note: Must be on the QueuedTask.Run()
  //UnitFormatType.Angular, UnitFormatType.Area, UnitFormatType.Distance, 
  //UnitFormatType.Direction, UnitFormatType.Location, UnitFormatType.Page
  //UnitFormatType.Symbol2D, UnitFormatType.Symbol3D
  var default_unit = DisplayUnitFormats.Instance.GetDefaultProjectUnitFormat(
                                                   UnitFormatType.Distance);
  // Use default_unit;
}

{
  // Note: Must be on the QueuedTask.Run()
  var unit_formats = Enum.GetValues(typeof(UnitFormatType)).OfType<UnitFormatType>().ToList();
  foreach (var unit_type in unit_formats)
  {
    var current_default = DisplayUnitFormats.Instance.GetDefaultProjectUnitFormat(unit_type);
    //Arbitrarily pick the last unit in each unit format list
    var replacement = DisplayUnitFormats.Instance.GetProjectUnitFormats(unit_type).Last();
    DisplayUnitFormats.Instance.SetDefaultProjectUnitFormat(replacement);

    var line = $"{current_default.DisplayName}, {current_default.UnitName}, {current_default.UnitCode}";
    var line2 = $"{replacement.DisplayName}, {replacement.UnitName}, {replacement.UnitCode}";

    System.Diagnostics.Debug.WriteLine($"Format: {unit_type}");
    System.Diagnostics.Debug.WriteLine($" Current default: {line}");
    System.Diagnostics.Debug.WriteLine($" Replacement default: {line2}");
  }
}