Dear Jan, The answer to your question is: Transactions of the IAU, vol. XXIIIB, "Proceedings of the 23rd General Assembly" ed. J. Andersen, Kluwer Academic Press, 1999, p. 141. This is the resoltion taken by Commission 36, and on page 181, there is the endorsment by Commission 25 ( Stellar Photometry and Polarimetry). Thank you for your interest in this question. Best regards Roger