By Emily Morgan: Political Correspondent
We now know what the Lib Dems are not prepared to back down on in the event of coalition trading.
Six red lines, all of which I think are relatively achievable for any party.
Admittedly the Tories might find it hard to accept their demands on welfare cuts; there will inevitably be horse trading on this.
And for Labour, will they ever be prepared to set a timetable for balancing the books? Public sector pay increases might also be a tricky one, but not out of the question.
The story today then is not what the main parties will accept, but what they'll demand.
The most interesting is that the Tories will insist on an in/out referendum on Europe in 2017.
Will Nick Clegg accept that in return for his red lines? I asked him just that. Over and over again and he simply wouldn't answer the question. He skirted around it.
The closest he came to an answer was to tell me that: "I accept, as a grown up politician, that if no one wins outright there is give and take about what is included in a coalition government agreement.
"I couldn't have been clearer about the things I will not compromise on, and beyond that is up to the British people to tell the politicians and political parties what kind of mandate they have to insist on their red lines".
So there will be give and take. Nick Clegg knows there's little hope of a coalition between the Conservatives and the Lib Dems if they rule out a referendum so, of course, there's room for negotiation on it.
Why won't Nick Clegg be open about that then? Well for one, I reckon the Lib Dems think at this point it would serve the interests of the Tories much more than those of the voters.
We'll see about that on Friday morning.