Should bank chairmen kill bonuses?
At what monetary threshold does a bonus become "a ludicrous sky-high" bonus?
The banks would quite like to know, because the deputy prime minister this morning told the Today programme that the coalition might well impose an additional punitive tax on them if they remunerate their superstars in that kind of "offensive" (Nick Clegg's words) way.
Well "sky high" - in the matter of pay - is a relative term. For most people, a bonus of £10,000 is a fortune. But we can be pretty sure Nick Clegg is not taking a pop at payments of that magnitude.
What about £100,000? Is that acceptable to him? Probably.
Or £500,000? That may be bordering on the "offensive" to the Lib Dem leader.
And is it £1m or £5m that's definitively intolerable?
This national obsession with bankers' pay - as evidenced by the bonus-bashing at the Lib Dem conference - may be fully justified.
After all, it seems odd and even obscene to many that institutions so recently rescued by taxpayers - and still explicitly or implicitly underwritten by taxpayers - should pay so lavishly.
But this fixation with the heft of the banks' wedge may not be healthy for the banks or for the economy.
Bank bosses have told me they are devoting an inordinate amount of time to thinking about how to pay their people what's necessary to honour their contracts and retain their services, while not paying so much that alienated politicians, media and populace become determined to pull their houses down.
Right now, what laughingly passes for a strategy to deal with this is a hope that the recent worsening in investment banks' performance continues for another couple of months, so that market forces force the banks to pay their people less than last year.
Even if their perverse wish for the froth to be wiped off their revenues is granted, seven-figure comp will still be what Santa brings to thousands of bankers - while hundreds of thousands of non-bankers fear for the security of their jobs.
So bank chairman and chief execs may have no alternative but to revive their collusive habits, and agree some kind of bonus moratorium among themselves.
How likely is it that they can agree a voluntary pay policy among themselves? Well, they made a half-hearted attempt last year and conspicuously failed.
But if they do little to collectively address public concerns about bankers' rewards, they are taking a not-very calculated risk that the furore will blow over.
The last time they took such a risk - namely when they thought the boom times in markets would never finish - it didn't end well.
Update 1210: A voluntary moratorium on bonuses won't happen, a senior banker tells me, because it would be illegal.
Here are his fascinating remarks:
"If a chairman decided to unilaterally disarm (ie slash bonuses) they would commit commercial harm and fail in their duties.
"If the market is producing an outcome that is unacceptable then regulators must regulate. Why has the Government not set up an independent pay commission or better still asked Vickers (the Treasury's bankig commission) to examine this issue alongside everything else?
"There is no realistic industry solution consistent with market rules and the legal responsibilities of directors."
So there you have it. If the government wants the banks to show bonus restraint, it may have to impose a pay policy on them.