embedding: A node's screens can be displayed inside another page you control, such as an intranet portal, a wallboard, or an existing operations site. Browsers refuse to embed a page across sites unless it says who may do so, which is why this previously showed up as an empty frame with no error. Set `FRAME_ANCESTORS` on the node to the sites you want to allow, space separated. Leave it unset and nothing changes: the node stays embeddable only by itself. Set it to `'none'` to block embedding outright.