SF_13.2, SF_13.3, SF_14.0, SF_14.1, SF_14.2, SF_14.3 - https://www.progress.com/documentation/sitefinity-cms/autogenerated-field-types/

DemoEnum.cs

using System.ComponentModel;
using Progress.Sitefinity.Renderer.Entities.Content;
using Progress.Sitefinity.Renderer.Designers.Attributes;

namespace SitefinityWebApp
{
    public class DemoEnum
    {
      //Single option enumerator 
      
      [DefaultValue(EnumSingle.Value2)]
      public EnumSingle EnumDefaultValue { get; set; }
        
      //Multiple option enumerator 
      
      [DefaultValue(EnumMultiple.Value1 | EnumMultiple.Value2)]
      public EnumMultiple EnumDefaultValueMultiple { get; set; }
      }
    
    public enum EnumSingle
    {
      Value1,
      Value2,
      Value3
    } 
    
    [Flags]
    public enum EnumMultiple
    {
      Value1 = 0x01,
      Value2 = 0x02,
      Value3 = 0x04
    }
}