Specifically, the Bank decided in 1 / 15  BIS central bankers' speeches  February 1999 to encourage the uncollateralized overnight call rate to move “as low as possible,” which means at virtually zero percent, by providing the market with more funds than necessary for financial institutions to meet their reserve requirements.
In addition, it explicitly committed to continuing with the zero interest rate policy “until deflationary concern is dispelled.” While the impact of that policy was called the policy duration effect at the time, the policy is based on the same idea as what later was to be called forward guidance, in that it enhances monetary easing effects by guiding the future policy path.