The Bank of Japan held its first Monetary Policy Meeting under new antisecrecy rules Friday and immediately announced that the Policy Board unanimously decided to leave monetary policy and the 0.5 percent official discount rate unchanged.The new format, adopted in advance of the April enforcement of the new Bank of Japan Law, aims to improve the transparency of the central bank's policymaking procedures. The meeting lasted from about 9 a.m. to 1:30 p.m. without intermission, a BOJ spokesman said.All six Policy Board members, including BOJ Gov. Yasuo Matsushita, were present, along with Senior Deputy Gov. Toshihiko Fukui and two executive directors, according to the spokesman. A summary of the meeting -- including the matters discussed and who supported or opposed a policy change -- will be released March 3.Under the new rules, the BOJ must in principle hold policy-setting meetings around the 10th and 25th of each month. Any decision, including one not to change policy, is to be announced immediately after each meeting, and the contents of the discussion are to be published a month later.In the past, the Policy Board met twice a week and held other meetings at irregular, unannounced dates, keeping its policymaking process secret. Its next meeting is Feb. 13.