IList<DisplayUnitFormat> GetPredefinedProjectUnitFormats( 
   UnitFormatType unitFormat
)

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

  foreach (var unit_format in unit_formats)
  {
    var units = DisplayUnitFormats.Instance.GetPredefinedProjectUnitFormats(unit_format);
    System.Diagnostics.Debug.WriteLine(unit_format.ToString());

    foreach (var display_unit_format in units)
    {
      var line = $"{display_unit_format.DisplayName}, {display_unit_format.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

  //Get the full list of all available location units
  var all_units = DisplayUnitFormats.Instance.GetPredefinedProjectUnitFormats(
                                                      UnitFormatType.Location);
  //keep units with an even factory code
  var list_units = all_units.Where(du => du.UnitCode % 2 == 0).ToList();

  //set them as the new location unit collection. A new default is not being specified...
  DisplayUnitFormats.Instance.SetProjectUnitFormats(list_units);

  //set them as the new location unit collection along with a new default
  DisplayUnitFormats.Instance.SetProjectUnitFormats(
                                          list_units, list_units.First());

  //Note: UnitFormatType.Page, UnitFormatType.Symbol2D, UnitFormatType.Symbol3D
  //cannot be set.
}