When embedding items, normally a new RenderContext is created and code within the page to be embedded has no way to get to state declared in the item that does the embed. We call this the 'sandbox' principle.

The UseSandbox parameter can set to 'false' to enable access to parent state in the child item.

The Sys.EvalInHost() Viper method can then be used to execute code in the embedding host or parent item.