All central banks have the long-term goal to maintain price stability which is a prerequisite for sustainable growth of the economy. The key is how we define and attain price stability. Almost all central banks have a numerical expression of price stability as they understand, define or target.
In the case of Japan, the Bank of Japan has provided its “understanding of medium- to long-term price stability.” The UK has an inflation targeting framework. These numerical expressions play an important role, since independent central banks have to be accountable with respect to their conduct of monetary policy.