CONCLUSIONS

It has been shown that short and medium term sub-micron orbit stability can be achieved in 3rd generation light sources. Fast orbit feedback systems and ``top-up'' operation are key ingredients to reach this level of stability. The stability of beam line components apart from X-BPMs has not been discussed. But it is evident that the achieved stability needs to be maintained throughout the beam line. To this end fast feedbacks on monochromators and other optical components have the potential to improve the stability of the beam line optics considerably [23]. The author would specifically like to thank Boris Keil, Thomas Schilcher, Volker Schlott and Andreas Streun for many fruitful discussions. The author gratefully acknowledges contributions from many other colleagues.