State how every read of a name stays on one pick, and why a fresh read leaves it

pick.go

@@ -141,6 +141,11 @@ func (sc renderScope) frameOf(scope *nameScope) *pickFrame {
 	return nil
 }
 
+// readName reads a from its name's pick in the frame rendering the name's scope. Every read of
+// one pick stays on it: the pick keeps each path's value and variant in its memo and its rows in
+// its pins. A read entering another category takes the frames of the name scopes there from the
+// memo too (enter), and renderFrame finds them and opens none. So {a.street} and {a.postal-code} in
+// data/sv_SE/address.json read one pick of the name l that data/geo/SE/address.json binds.
 func readName(s *drawstate.State, sc renderScope, a arm) readValue {
 	f := sc.frameOf(a.named.scope)
 	if f == nil {