diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Arrangement_on_surface_2.txt b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Arrangement_on_surface_2.txt
index cea994341a9..b4bff8ed2db 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Arrangement_on_surface_2.txt
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Arrangement_on_surface_2.txt
@@ -117,8 +117,8 @@ special type of objects. They must, however, supply the relevant
 traits class, which mainly involves algebraic computations. A traits
 class also encapsulates the number types used to represent coordinates
 of geometric objects and to carry out algebraic operations on them. It
-encapsulates the type of coordinate system used (e.g., Cartesian and
-Homogeneous), and the geometric or algebraic computation methods
+encapsulates the type of coordinate system used (e.g., %Cartesian and
+homogeneous), and the geometric or algebraic computation methods
 themselves. The precise minimal sets of requirements the actual traits
 classes must conform to are organized as a hierarchy of concepts; see
 Section \ref aos_sec-geom_traits.