diff --git a/src/direction_type.h b/src/direction_type.h
--- a/src/direction_type.h
+++ b/src/direction_type.h
@@ -42,7 +42,7 @@ DECLARE_POSTFIX_INCREMENT(Direction)
 
 /** Define basic enum properties */
 template <> struct EnumPropsT<Direction> : MakeEnumPropsT<Direction, byte, DIR_BEGIN, DIR_END, INVALID_DIR, 3> {};
-typedef TinyEnumT<Direction> DirectionByte; // typedefing-enumification of Direction
+typedef TinyEnumT<Direction> DirectionByte; ///< typedefing-enumification of Direction
 
 
 /**
@@ -92,7 +92,7 @@ DECLARE_POSTFIX_INCREMENT(DiagDirection)
 
 /** Define basic enum properties */
 template <> struct EnumPropsT<DiagDirection> : MakeEnumPropsT<DiagDirection, byte, DIAGDIR_BEGIN, DIAGDIR_END, INVALID_DIAGDIR, 2> {};
-typedef TinyEnumT<DiagDirection> DiagDirectionByte; // typedefing-enumification of DiagDirection
+typedef TinyEnumT<DiagDirection> DiagDirectionByte; ///< typedefing-enumification of DiagDirection
 
 
 /**
@@ -130,6 +130,7 @@ enum Axis {
 	AXIS_END,            ///< Used for iterations
 	INVALID_AXIS = 0xFF, ///< Flag for an invalid Axis
 };
+/** Helper information for extract tool. */
 template <> struct EnumPropsT<Axis> : MakeEnumPropsT<Axis, byte, AXIS_X, AXIS_END, INVALID_AXIS, 1> {};
 
 #endif /* DIRECTION_TYPE_H */