"Unconventional" monetary policy is only supposed to happen when official interest rates are at zero and plain old vanilla policies have nowhere to go. So why did the Bank of England confirm today that it was poised to buy up "high quality" corporate debt?
This is not "quantitative easing". Nor is it printing money. But, by the governor's own admission, it is highly unconventional (in fact, he says it's an "unconventional unconventional measure", but let's not go there). And it's despite the fact that official interest rates are still at 1.5%.
One answer is that this is all about confidence, and after playing catch up for so much of the credit crunch, the authorities need to do everything to show they're thinking ahead.
Another is that buying up corporate debt theoretically has a distinct objective - improving the credit environment by reducing the yields in those markets.
But there is a more general point: as the economist David Miles noted in this week's Green Budget from the IFS. The Bank may well hope to avoid taking the policy rate to zero - for the sake of the banks.
Their problem is that whenever official rates go down, they are under heavy pressure to cut lending rates in tandem, but many deposit rates are already very low and can go no lower. So margins shrink further, and the banks get squeezed even more than they are already.
The upshot: the Bank of England is likely to be doing a lot of unconventional things long before rates get to zero.
However, a senior economist I spoke to in Davos reminded me that we've heard this argument before - in fact, the Federal Reserve tried the same thing last year. It didn't work.
If the central bank is successful in increasing banks' cash reserves, overnight market rates can go down close to zero, even if official rates are still positive.
The Fed found the anomaly sufficiently uncomfortable that it fairly quickly brought the official rate down too. As it confirmed in yesterday's gloomy statement, it is going to stay there for a long time.
Economists I've spoken to here think the UK will end up in the same place. But it's possible they will be happy with overnight rates being out of step with Bank rate.
After all, the pressure on commercial lenders is to match "headline" interest rate changes. The mainstream press now pays more attention to the overnight markets than it used to, but it's hardly the stuff of headlines.
Whatever happens, it's uncharted territory for the UK's monetary policy and we are about to step into it.