void SetProjectUnitFormats( 
   IList<DisplayUnitFormat> availableUnits,
   DisplayUnitFormat defaultUnit
)

{
  // 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.
}

{
  //UnitFormatType.Angular, UnitFormatType.Area, UnitFormatType.Distance, 
  //UnitFormatType.Direction, UnitFormatType.Location
  var angle_units = DisplayUnitFormats.Instance.GetProjectUnitFormats(UnitFormatType.Angular);

  //Edit the display name of each unit - append the abbreviation
  foreach (var unit in angle_units)
  {
    unit.DisplayName = $"{unit.DisplayName} ({unit.Abbreviation})";
  }
  //apply the changes to the units and set the default to be the first entry
  DisplayUnitFormats.Instance.SetProjectUnitFormats(angle_units, angle_units.First());
  //The project must be saved to persist the changes...
}