There isn't such property. You could handle LinkCreating and LinkModifying to prevent the operation when the target node has the maximum number of incoming or outgoing links.

I hope that helps,
Stoyan

I tried to write this code, but it gets executed in a loop the moment I try to create a link from a start task;
private void diagram_LinkCreating(object sender, LinkValidationEventArgs e)
       {

// if Start Task
DiagramLinkCollection links = startNode.GetAllLinks();
                   if (links.Count > 1)
                   {
                       HandleErrors("Only one out bound route is allowed per Start task");
                       e.Cancel = true;
                       return;
                   }
}
what is th ebest way to cancel the event.