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

//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...