-\section{Notation}
+\stdsection{Notation}
+
+Throughout, any free variables are implicitly universally quantified
+at the outermost level.
\begin{basedescript}{
\desclabelwidth{5em}
are respectively the base and tip git branches. $\p$ may be used
where the context requires a set, in which case the statement
is to be taken as applying to both $\py$ and $\pn$.
-All of these sets are disjoint. Hence:
+All of these sets will be disjoint by construction
+(see Invariants, below). Hence:
+
+\item[ $\set A$, $\set P$, $\ldots$ ]
+Arbitrary sets of commits. Maybe $\set P = \p$ i.e.\ some $\py$ or $\pn$, but
+maybe not.
\item[ $ \patchof{ C } $ ]
Either $\p$ s.t. $ C \in \p $, or $\bot$.