+XBT_LOG_NEW_SUBCATEGORY(gras,XBT_LOG_ROOT_CAT,"All GRAS categories");
+XBT_LOG_NEW_SUBCATEGORY(xbt,XBT_LOG_ROOT_CAT,"All XBT categories (gras toolbox)");
+XBT_LOG_NEW_SUBCATEGORY(surf,XBT_LOG_ROOT_CAT,"All SURF categories");
+XBT_LOG_NEW_DEFAULT_SUBCATEGORY(log,xbt,"Loggings from the logging mecanism itself");