Contains either a moniker to create and call the method on (string), or an object to call the method on.
If set to a moniker, the moniker is instantiated when either
invoke or
asyncInvoke is called,
and released when the call completes. If set to an object, a reference is held on that object until
it's replaced (via SetProperty), or until the message instance itself is destroyed.
var messageObj = shell.serviceManager.basics.message;
var target = messageObj.target;