Scottish independence: The struggle for undecided voters
Now that the clock shows that there are just six months to go to polling day, the minds of campaigners on both sides are becoming increasingly concentrated on how they might win over converts to their cause.
Inevitably that means they have their eyes in particular on those who say they are still 'undecided' about which way to vote.
Not that there is one clear block of 'undecided' voters. In fact pollsters have discovered that how many people say they are undecided depends on what question they are asked.
Most polls of referendum voting intention ask people how they would vote if the referendum were held tomorrow.
On average they find that when asked that question no more than 15% of Scots are unclear what they would do.
It is by no means a particularly large number as compared, for example, with the proportion who said they were undecided what to do just two or three months in advance of the 2011 referendum on the Alternative Vote.
However, TNS BMRB ask their respondents how they intend to vote in the referendum in September. Around twice as many people say they don't know in response to that question.
Meanwhile, the most recent Scottish Social Attitudes survey found that as many as 33% were undecided when they were asked what they would do in September.
At the same time, polls conducted by Ipsos MORI and ICM suggest that up to 20% of those who say they know how they would vote if the referendum were held tomorrow admit that they might change their mind between now and September.
So, rather than being a clear, distinct group of 'undecided', voters are at different points on a spectrum of indecision.
Some - but perhaps not that many - still have no idea what they will do. In truth some of these will be people who in the end simply will not vote.
Others have at least an inkling of what they will do, or even quite a clear preference, but are prepared to admit they might yet change their minds.
This latter group may potentially be up for grabs - but they will not all necessarily be that easy to dislodge from their current inclination.
But who are the voters who are least not yet wholly committed to one side or the other?Core undecideds
According to the Scottish Social Attitudes survey they consist disproportionately of people for whom the choice between independence and remaining in the UK looks like a particularly tough one to have to make.
They are particularly likely to be voters who feel both Scottish and British and whose preferred outcome would be more devolution within the framework of the UK.
The report from the Labour party on more devolution, together with last Friday's promise of more devolution made by the Prime Minister, are doubtless in part aimed at this group.
Indeed when voters who say they are undecided are asked what at least they think they would do in the referendum, typically they prove to be more likely to say they will vote Yes than are Scots as a whole.
So the No side probably do have to make an effort to reach out to this group if it is to avoid seeing its lead narrowing yet further during the course of the next six months.
Voters' indecision is not though all just about the politics of the referendum.
Women are also more likely than men to say they are undecided. That is because they feel they do not know enough about the seemingly complicated issues at stake.
But perhaps they are simply being more honest?
John Curtice is professor of politics at Strathclyde University, and chief commentator at whatscotlandthinks.org, where details of all of the referendum polls can be found.