Delete selection, exclude a particular node

Supose that you select three nodes: A, B, C in the diagram. Then you press “del” key.
I need to remove the A node from e.subject collection event, so only will be deleted B and C.
How I can do that?

Well, you could set or bind Part.deletable to false on node A. That will automatically cause CommandHandler.deleteSelection to skip over node A, because the command does not delete non-deletable top-level Parts.

If node A is supposed to be deleted in other circumstances, such as if node A were not selected first, or if node A were the only selected node, then you would need to override the CommandHandler.deleteSelection method to first set Part.deletable to false on all of those Parts that you don’t want to delete, and then call the base method to perform the usual work.

Thank you!, this is that I wanted.

 new go.Binding("deletable", "", function(data){
	return data.elementType !== 'stateInitial';

Better would be:

  new go.Binding("deletable", "elementType", function (e) { return e !== "stateInitial"; })

Ok, thanks!