using System;

using System.Collections.Generic;

using System.Linq;  

public class Program

{

     public enum PermissionIndex

    {

        CMISRead = 0,

        List = 1,

        ListViewableOnly = 2,

        View = 3,

        RequestDownload = 4,

        DownloadRenditionOnly = 5,

        DownloadOriginal = 6,

        AddToCart = 7,

        Execute = 8,

        ApproveDownload = 9,

        SubmitAsset = 10,

        ApproveSubmission = 11,

        CreateAsset = 12,

     }

    public static void Main()

    {

    var x=  ParseUserPermissionsList("CreateAsset,nonexisiing");

    }

        private static List<PermissionIndex> ParseUserPermissionsList(string userPermissionsList)

        {

            var ignoreCase = true;

            var permissionsList = string.IsNullOrWhiteSpace(userPermissionsList) ? new List<PermissionIndex>() :

                userPermissionsList.Split(',').Select(index => (PermissionIndex)Enum.Parse(typeof(PermissionIndex), index, ignoreCase)).ToList();

            return permissionsList;

        } 

}