Index: trunk/MagicSoft/Mars/mgeom/MGeomPix.cc
===================================================================
--- trunk/MagicSoft/Mars/mgeom/MGeomPix.cc	(revision 1458)
+++ trunk/MagicSoft/Mars/mgeom/MGeomPix.cc	(revision 1459)
@@ -30,4 +30,8 @@
 // This container stores the geometry (position) information of
 // a single pixel together with the information about next neighbors.
+//
+// The BIT(22) and BIT(23) is used to flag the pixels in the outer
+// and outermost ring. Please don't use this bits in conjuction with
+// MGeomPix.
 //
 ////////////////////////////////////////////////////////////////////////////
Index: trunk/MagicSoft/Mars/mgeom/MGeomPix.h
===================================================================
--- trunk/MagicSoft/Mars/mgeom/MGeomPix.h	(revision 1458)
+++ trunk/MagicSoft/Mars/mgeom/MGeomPix.h	(revision 1459)
@@ -12,6 +12,8 @@
 private:
     enum {
-        kIsInOutermostRing = BIT(14),
-        kIsInOuterRing     = BIT(15)
+        kIsInOutermostRing = BIT(22),
+        kIsInOuterRing     = BIT(23),
+        kUserBits          = 0x1fc000 // 14-21 are allowed
+
     };
 
@@ -51,4 +53,15 @@
     Bool_t IsInOuterRing() const     { return TestBit(kIsInOuterRing); }
 
+    /*
+     //
+     // These function are for future usage. They are not virtual in
+     // root by now.
+     //
+     void SetBit(UInt_t f, Bool_t set) { set ? TObject::SetBit(f) : TObject::ResetBit(f); }
+     void SetBit(UInt_t f)    { TObject::SetBit(f & kUserBits); }
+     void ResetBit(UInt_t f)  { TObject::ResetBit(f & kUserBits); }
+     void InvertBit(UInt_t f) { TObject InvertBit(f & kUserBits); }
+     */
+
     ClassDef(MGeomPix, 1) // Geometry class describing the geometry of one pixel
 };