Change the representation type of vpubOld and vpubNew to be unsigned.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

protocol/protocol.tex

@@ -2800,10 +2800,10 @@ a \transaction as an instance of a \type{JoinSplitDescription} type as follows:
 Bytes & \heading{Name} & \heading{Data Type} & \heading{Description} \\
 \hhline{|=|=|=|=|}
 
-\setchanged 8 &\setchanged $\vpubOldField$ &\setchanged \type{int64\_t} &\mbox{}\setchanged
+\setchanged 8 &\setchanged $\vpubOldField$ &\setchanged \type{uint64\_t} &\mbox{}\setchanged
 A value $\vpubOld$ that the \joinSplitTransfer removes from the \transparentValuePool. \\ \hline
 
-8 & $\vpubNewField$ & \type{int64\_t} & A value $\vpubNew$ that the \joinSplitTransfer inserts
+8 & $\vpubNewField$ & \type{uint64\_t} & A value $\vpubNew$ that the \joinSplitTransfer inserts
 into the \transparentValuePool. \\ \hline
 
 32 & $\anchorField$ & \type{char[32]} & A merkle root $\rt$ of the \noteCommitmentTree at
@@ -3574,6 +3574,15 @@ The errors in the proof of Ledger Indistinguishability mentioned in
 
 \nsection{Change history}
 
+\subparagraph{2016.0-beta-1.8}
+
+\begin{itemize}
+    \item Change the representation type of $\vpubOldField$ and $\vpubNewField$
+          to \type{uint64\_t}. (This is not a consensus change because the type of
+          $\vpubOld$ and $\vpubNew$ was already specified to be $\range{0}{\MAXMONEY}$;
+          it just better reflects the implementation.)
+\end{itemize}
+
 \subparagraph{2016.0-beta-1.7}
 
 \begin{itemize}