X <-> Y

Thanks to Laurent Moret-Bailly
https://stacks.math.columbia.edu/tag/0AF2#comment-7780

spaces-pushouts.tex

@@ -2089,7 +2089,7 @@ \section{Formal glueing of algebraic spaces}
 
 \noindent
 In Situation \ref{situation-formal-glueing} we consider the category
-$\textit{Spaces}(X \to Y, Z)$
+$\textit{Spaces}(Y \to X, Z)$
 of commutative diagrams of algebraic spaces over $S$ of the form
 $$
 \xymatrix{