Re : Passing parent scope to components is undocumented

The scope the custom tag was found within. By default, any attribute's values will be looked up within the current scope, but if you want to add values without needing the user to provide an attribute, you can set this up here. For example:

can.Component.extend({
    tag: "my-element",
    scope: function(attrs, parentScope){
      return new can.Map({title: parentScope.attr('name')});
    }
});

Notice how the attribute's value is looked up in my-element's parent scope.