Index: src/natools-s_expressions-enumeration_io.adb
==================================================================
--- src/natools-s_expressions-enumeration_io.adb
+++ src/natools-s_expressions-enumeration_io.adb
@@ -59,17 +59,17 @@
       function Value (Data : Atom) return Enum is
       begin
          return Enum'Value (To_Image (Data));
       end Value;
 
-      function Value (Data : Atom; Default : Enum) return Enum is
+      function Value (Data : Atom; Fallback : Enum) return Enum is
          Img : constant String := To_Image (Data);
       begin
          return Enum'Value (Img);
       exception
          when Constraint_Error =>
-            return Default;
+            return Fallback;
       end Value;
 
    end Typed_IO;
 
 end Natools.S_Expressions.Enumeration_IO;

Index: src/natools-s_expressions-enumeration_io.ads
==================================================================
--- src/natools-s_expressions-enumeration_io.ads
+++ src/natools-s_expressions-enumeration_io.ads
@@ -39,12 +39,12 @@
          --  Convert an enumeration value into an atom
 
       function Value (Data : Atom) return Enum;
          --  Convert an atom into an enumeration value
 
-      function Value (Data : Atom; Default : Enum) return Enum;
+      function Value (Data : Atom; Fallback : Enum) return Enum;
          --  Convert an atom into an enumeration value,
-         --  with a default value on invalid atom images
+         --  with a fallback value on invalid atom images
 
    end Typed_IO;
 
 end Natools.S_Expressions.Enumeration_IO;