+Documentation:
+
+To document the code use the following rules to allow extraction with doxygen.
+Do not save with comments. Not all comments have to be doxygen comments.
+
+- Use C comments in plain C files and use C++ comments in C++ files for one line
+ comments.
+- Use '/**' (note the two asterisks) to start comments to be extracted by
+ doxygen and start every following line with " *".
+- Use '\' to indicate doxygen keywords/commands (see below).
+- Use the '\deprecated' command to tell if the function is subject to be deleted
+ or to a complete rewrite.
+
+Example:
+
+To document functions or big structures:
+ /**
+ * \brief This is a short description of the function.
+ *
+ * This function does ...
+ *
+ * \param x1 This is the first parameter named x1
+ * \param y1 This is the second parameter named y1
+ * \return What the function returns
+ * You can extend that return description (or anything else) by indenting the
+ * following lines until the next empty line or the next keyword/command.
+ * \see Cross reference
+ */
+
+To document members of a structure that have to be documented (use it at least
+for big structures) use the '/**<' format:
+ int counter; /**< This counter counts images */
+
+For further documentation about doxygen see
+http://www.stack.nl/~dimitri/doxygen/manual.html. For the possible commands you
+can use see http://www.stack.nl/~dimitri/doxygen/commands.html.
+
+But in case just think about that the documentation is for other developers not
+for the end user. So keep the focus.