ProgIdAttribute.cs

namespace System.Runtime.InteropServices
{
    [AttributeUsage(AttributeTargets.Class, Inherited = false)]
    [ComVisible(true)]
    public sealed class ProgIdAttribute : Attribute
    {
        internal string _val;

        public string Value => _val;

        public ProgIdAttribute(string progId)
        {
            _val = progId;
        }
    }
}