<PackageReference Include="NETStandard.Library" Version="2.0.0" />

System.Net.Sockets.SocketAsyncOperation

public enum SocketAsyncOperation
namespace System.Net.Sockets { public enum SocketAsyncOperation { Accept = 1, Connect = 2, Disconnect = 3, None = 0, Receive = 4, ReceiveFrom = 5, ReceiveMessageFrom = 6, Send = 7, SendPackets = 8, SendTo = 9 } }