diff -r 84e75e8f2fd2 -r 98adf9276de0 doc/maps.dox
--- a/doc/maps.dox	Sun Apr 04 09:16:35 2004 +0000
+++ b/doc/maps.dox	Sun Apr 04 09:17:58 2004 +0000
@@ -1,10 +1,13 @@
 /*!
 
-\page maps How to write maps
+\page maps How to write your own maps
 
 \section read-maps Readable Maps
 
-It is quite easy to write your own readmap for the edges or nodes of a graph.
+The readable maps are very frequently used as the input of the
+algorithms.  For this purpose the most straightforward is to use the
+maps provided by Hugo's graph structres. Very often however, it is more
+convenient and/or more efficient to write your own readable map.
 
 You can find some example below.
 
@@ -14,14 +17,32 @@
 struct MyMap 
 {
   typedef double ValueType;
-  double operator[](Graph::EdgeIt e) const { return M_PI;}
+  double operator[](Graph::Edge e) const { return M_PI;}
 };
 \endcode
 
+An alternative way to define maps. For this, \c MapBase seems to
+be a better name then \c NullMap
+
+\code
+struct MyMap : public MapBase<Edge,double>
+{
+  double operator[](Graph::Edge e) const { return M_PI;}
+};
+\endcode
+
+Or if we had \c KeyType and \c ValueType
+
+\code
+struct MyMap : public MapBase<Edge,double>
+{
+  ValueType operator[](KeyType e) const { return M_PI;}
+};
+\endcode
+
 
 Here is a more complex example. It provides a length function which is obtained
 from a base length function modified by a potential difference.
-\todo Please improve on the english. 
 
 \code
 class MyLengthMap 
@@ -32,7 +53,7 @@
 public:
   typedef double ValueType;
 
-  double operator[](Graph::EdgeIt e) const {
+  double operator[](Graph::Edge e) const {
     return ol.get(e)-pot.get(v)-pot.get(u);
   }
   
@@ -41,5 +62,6 @@
 };
 \endcode
 
+\todo Please improve on the english. 
 \todo Don't we need \e to \e require a 'typedef xxx KeyType' tag, as well?
 */