I will use RuleMaker to express the core idea for RFC 4271: "Border Gateway Protocol 4 (BGP-4)", because I want to illustrate this for the organizer of the November 2025 panel session at IETF124 (Alvaro Retana who wrote Cisco's book on the topic: https://www.ciscopress.com/store/optimal-routing-design-9781587051876 )

Here are the sentences I've got to shoehorn into the DWD expression structure.

Routes learned from an eBGP peer are propagated to all peers.
Routes learned from an iBGP peer are propagated only to eBGP peers.
Routes originated locally are propagated to all peers.
Routes learned from iBGP peers are not sent to other iBGP peers, ensuring that a full mesh topology is maintained to avoid routing loops within the AS.

Source: https://www.rfc-editor.org/rfc/rfc4271

You might want to try doing this too, on your own, before seeing mine. https://prod-xalgorithms-v4.onrender.com/