We need to consider this for $D=L$ and also for $D=R$ ($R \in \set
R$).
-For $D=L$, if $L \in \pn$ then $C \in \pn$, OK; whereas if
-$L \not \in \pn$ Bases' Children is inapplicable.
+For $D=L$: $L \in \pn$ so $\pd = \p$. And $C \in \pn = \pdn$. Bases'
+Children applies and is satisfied.
-For $D=R$,
-xxx up to here?
-
-If $L \in \py, R \in \py$: not applicable for either $D=L$ or $D=R$.
-
-If $L \in \py, R \in \pn$: not applicable for $L$, OK for $R$.
-
-Other possibilities for $L \in \py$ are excluded by Tip Merge.
-
-If $L \in \pn, R \in \pn$: satisfied for both $L$ and $R$.
-
-If $L \in \pn, R \in \foreign$: satisfied for $L$, not applicable for
-$R$.
-
-If $L \in \pn, R \in \pqy$: satisfied for $L$, not applicable for
-$R$.
-
-Other possibilities for $L \in \pn$ are excluded by Base Merge.
-
-If $L \in \foreign$: not applicable for $L$; nor for $R$, by Foreign Merges.
+For $D = R \in \set R, R \in \pn$: $D \in \pn, \pd = \p, C \in \pn$ as
+for $D = L$.
+For $D = R \in \set R, R \in \foreign$, or $R \in \pqy$: $D \not\in
+\pdn$ so Bases' Children does not apply.
+Other possibilities for $D \in \set R$ are excluded by Ingredients.