   consts and stuff
 Vector3& Center ();    const Vector3& Center () const;  How would the compiler know which version to use?  I didn''t previously know that this was possible but I''ve seen Eberly use it in his Magic Software code.  
  one is for retrieving, the other for setting:minZ = bOBB.Center().z - bOBB.Extent(2); // retrieving bBox.Center().x = min.x + dX*0.5f; // setting  the retrieval is done via the const version of the function.at least that''s the way i use ''em. ;  If the object being operated-on is a const object, it can only use the second.  If the object is non-const, my compiler chooses the first.  I don''t believe the compiler can use the return value to determine the function type (IANALL), so I think it just calls the function that corresponds to the type of object.Example:   class C{public:C &foo (){return *this;}const C &foo () const{return *this;}};int main (){C mc;C &rc = mc.foo (); // calls C &foo ()const C &crc = mc.foo (); // so does this since mc is non-constreturn 0;}  