-for a non-looped tree of nodes. This has probably never, reliably,
-been achieved in practice; certainly not recently. This document
-describes a complete replacement for that protocol. It allows a
+for a non-looped tree of nodes. This environment has probably never, reliably,
+been achieved in practice; certainly not recently.
+
+There have always been loops, sometimes bringing the network to its
+knees. In modern usage, both in order to get some resilience and also
+to expedite information flow, we use internet based, deliberately
+looped networks with filtering. Whilst this works, after a fashion, there
+are all sorts of problems that the current PC protocol can never
+address.
+
+This document
+describes a complete replacement for the PC protocol. It allows a