Class vs. Attribute

AttributeVsClass.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using PX.Objects;
using PX.Data;
using PX.Data.BQL;

namespace Aktion.Common.Acumatica.NoCodeChanges
{

    public class BarCodeIDAttribute : Attribute
    { }

    public abstract class BaseGuid : IBqlGuid
    {
        public BaseGuid() { }

        BaseGuid(Guid guid)
        {
            _Guid = guid;
        }

        private Guid _Guid;

        public Guid Guid
        {
            get { return _Guid; }
            set { _Guid = value; }
        }
    }

    [BarCodeID]
    public class BarcodeIDField : BaseGuid
    {
    }

    public class BaseDAC : IBqlTable { }

    public class MyDAC : BaseDAC
    {
        public abstract class barcodeID : BaseGuid
        {

        }

        public virtual BarcodeIDField BarcodeID { get; set; }
    }

}