MAIN development was and still is inspired via communications with MAIN users and other crystallographers all over the world. I wish to thank all MAIN fans and other users who helped me to decide what to do. However, there are a few persons and groups, for who I feel that explicit acknowledgments are mandatory.

I am grateful to all members of Rober Huber's group in Martinsried, who were and are still the major group confronted with the fresh outcoming MAIN releases and bugs therein. As first, without doubt the most enthusiastic MAIN fan, Hans Brandstetter. In particular I wish to mention Peter Hof, Lars Prade, Tarmo Plom, Manuel Than and Tim Mather (the friendly spirit to the greetings page.)

Similarly, my coworkers in Ljubljana are acknowledged too. They have to deal with fatal bugs, sometimes introduced on a daily basis. Gregor Guncar, in particular, deserves his name to be mentioned.

Jan Loewe compiled the first Mac (OSX) version of MAIN and on going suggestions on program development since his arrival to Cambridge.

On the automation pathway Wladek Minor and his coworkes (Maksymilian Chruszcz, Marcin Cymborowski, Zbyszek Otwynowski, ...) were indispensable for numerous discussions and for providing the test cases, without which a large extent of development of automated chain tracing would not have been possible.

Sasha Urzhumtsev and his crew from Nancy (Pavel Afonine, Andrej Fokine) are acknowledged for their help with the bulk solvent correction procedure and incorporation of their target functions based on maximum likelihood approach used in refinement and map calculations. These tools were built into MAIN during their short visit in Ljubljana in November 2002.

• Fokine, A. and Urzhumtsev, A. (2002) Flat bulk-solvent model: obtaining optimal parameters. Acta Crystallogr. D Biol. Crystallogr. (58), 1387-92.
• Lunin, V.Y., Afonine, P.V., Urzhumtsev, A.G. (2002) Likelihood-based refinement. I. Irremovable model errors. Acta Cryst. A58, 270-82.

Lynn Ten Eyck is gratefully acknowledged for providing his FFT routines.

Saulius Grazulis is acknowledged for creating the first Perl script generating the "html" version of MAIN "Keyword Index".

When refining or minimizing protein or nucleic acids models please cite:

• Engh, R.A. and Huber, R. (1991) Accurate bond and angle parameters for X-ray protein structure refinement. Acta. Cryst A47, 392-400.
• G. Parkinson, J. Vojtechovsky, L. Clowney, A.T. Brunger, H.M. Berman (1996) New Parameters for the Refinement of Nucleic Acid Containing Structures, Acta Cryst. D52, 57-64.