public abstract class Mailbox<TSys, TUser> : MessageQueueMailbox
where TSys : MessageQueue
where TUser : MessageQueue

Public MustInherit Class Mailbox(Of TSys As MessageQueue, TUser As MessageQueue)
	Inherits MessageQueueMailbox

generic<typename TSys, typename TUser>
where TSys : MessageQueue
where TUser : MessageQueue
public ref class Mailbox abstract : public MessageQueueMailbox

[<AbstractClassAttribute>]
type Mailbox<'TSys, 'TUser when 'TSys : MessageQueue when 'TUser : MessageQueue> =  
    class
        inherit MessageQueueMailbox
    end