Note the Edwards curve neutral point.

misc/ecc-formulas.tex

@@ -138,7 +138,8 @@ For an Edwards curve, we consider the special case
 \begin{equation*}
   x^2 + y^2 = 1 + d x^2 y^2
 \end{equation*}
-See \url{http://cr.yp.to/papers.html#newelliptic}.
+See \url{http://cr.yp.to/papers.html#newelliptic}. The neutral point is
+$(0, 1)$.
 
 Affine formulas for addition, $(x_3, y_3) = (x_1, y_1) + (x_2,
 y_2)$: