--- a/igc.h	Sun Jan 29 00:38:40 2012 +0100
+++ b/igc.h	Sun Jan 29 01:51:02 2012 +0100
@@ -54,6 +54,10 @@
 class IGC {
   public:
 
+    IGC();
+    IGC(QTextStream&);
+    ~IGC();
+
     //! Read the IGC records.
     //!	\param s a (file) stream containing the records
     void read(QTextStream& s);
@@ -66,11 +70,13 @@
 
     Fix start() const { return start_; }	//!< the very first fix
     Fix landing() const { return landing_; }	//!< the very last fix
+    const QVector<QPointF>& altitude(Fix::Source) const;
 
   private:
     QString device_, pilot_, glider_;
     QDate date_;
     Fixes fixes_;
+    mutable QVector<QPointF>* altitude_[2];
 
     Fix start_;
     Fix landing_;