The Reserve Bank of New Zealand has detailed more of its thinking behind its limit on low deposit lending, saying in a briefing paper it is "learning by doing", to some extent, and may look at fresh "targeted interventions".Macro Financial Department adviser Lamorna Rogers wrote in the RBNZ's September Bulletin that the policy was no "silver bullet" and was still in its infancy."We do not see macro-prudential instruments as 'set and forget' tools; once deployed, there will be on-going assessments of their effectiveness, which will condition their use and their eventual release," Rogers wrote.Elsewhere in the paper she detailed how the policy might evolve."For example, it might be decided to target the intervention to reduce welfare costs, assuming it was still possible to meet a minimum effectiveness threshold," she said."An example would be targeting housing investors. The Reserve Bank is improving its capacity to undertake targeted interventions: for example, new data collections are being put in place, which will provide breakdowns of housing lending by categories such as investors, first-home buyers and businesses."