Whether $\baseof{C}$ is required, and if so what the value is, is
stated in the proof of Unique Base for each kind of commit.
-$C \haspatch \pq$ or $\nothaspatch \pq$ is represented as the
-set $\{ \pq | C \haspatch \pq \}$. Whether $C \haspatch \pq$
+$C \haspatch \pq$ or $\nothaspatch \pq$ is represented as a
+list of $\pq$ for which it is known that $C \haspatch \pq$;
+for any $\pq$ not listed, $C \nothaspatch \pq$.
+Whether to record $C \haspatch \pq$ in a new commit
is in stated
(in terms of $I \haspatch \pq$ or $I \nothaspatch \pq$
for the ingredients $I$)