Mrs Foster signed off on an impact assessment for the RHI scheme - it outlined the benefits, risks, and costs and is presented to the inquiry.

Mr Scoffield points to a section with two boxes for costs and benefits but neither is filled in with any figures, and those were the aspects considered in the CEPA report.

Image source, RHI Inquiry

"How were you able to indicate that you were satisfied abut the likely costs when the impact assessment you were given doesn't outline them?" asks Mr Scoffield.

Mrs Foster says she can only presume the boxes were left blank "because we hadn't had the final CEPA report" by the time she signed off on the document - only a draft had been published at that point.

She says she thinks she would have signed the risk assessment based on "the prose behind that page" and on the submission.

Mrs Hepper told the inquiry that it was "the working practice at the time" for there not be a note made of meetings with ministers.

Mrs Foster claims she didn't know that was happening, she accepts that it was not good practice but says it is the responsibility of civil servants to ensure notes were being taken.

Image source, Getty Images

The DUP leader suggests that the absence of notes in the case of DETI's energy division may be "indicative of the pressure" that its staff were under and perhaps "shortcuts were taken in order to deal with" the workload.

Sir Patrick Coghin notes that Dr Crawford was "confounded" to discover that notes were not being taken, and the inquiry chair adds: "You do wonder what is going in within this department."

Guidance for Stormont departments says that meetings involving ministers and officials should be minuted by civil servants.

Mrs Foster says she wasn't aware of that guidance and adds: "I just don't understand how things can run if you don't have a record of what decisions were taken at meetings - how do you refer back if there's nothing there?"

Image source, RHI Inquiry

Inquiry panellist Dr Keith MacLean (above) asks how the minister would've kept track of requests made at meetings to ensure they were carried out.

Mrs Foster says that if her private secretary was there she would have kept "action points" and would sometimes have followed up with an email.

It's "incontrovertible" that Mrs Foster's expectations of her "two trusted people" - her adviser Dr Crawford and DETI's energy boss Mrs Hepper - "were unfulfilled", says Sir Patrick.

"I just wonder about how this department was working in practice," he adds.

Image source, Getty Images

Mrs Foster "was somewhat taken aback" that there are no notes of the key meeting in June 2011 at which she decided on what form the RHI scheme would take.

"I would've expected... there to have been some sort of record of what I had said at the meeting, what [Mrs Hepper] had explained to me," she adds, saying that if they existed there "would clarity around all of this".

Sir Patrick presses Mrs Foster on why neither she nor Dr Crawford asked for notes when they were not forthcoming from her officials, and the DUP leaders says she "didn't see it as being my role".

There's an tense spell as chair Sir Patrick Coghlin suggests that the evidence the inquiry has seen to date points to DETI being "a dysfunctional department" at the time when Mrs Foster was leading it.

He notes that that Mrs Foster's ministerial adviser Dr Andrew Crawford didn't read crucial expert reports - that cost £100,000 to draw up - on which the RHI scheme was based.

Image source, RHI Inquiry

He also observes that no records or notes were made by DETI's energy boss Fiona Hepper of the key meeting at which Mrs Foster decided on what direction the RHI scheme would take.

Sir Patrick says: "These are the two people that you trusted."

The funding mechanism for the RHI scheme was unusual type, one that many of the civil servants who have appeared before the inquiry have said they had never encountered before - it's even been decribed as "quirky".

In simple terms, DETI had to cover any overspend that might have occurred and there would effectively be a penalty imposed of about 5% in the case of going over-budget.

Image source, RHI Inquiry

Mrs Hepper insists she did tell the minister about the funding set-up during the June 2011 meeting.

But Mrs Foster disagrees: "I was never made aware that was a special type of [funding]."

Mr Scoffield asks if, like other information from the meeting, Mrs Foster might simply have forgotten that the funding position was discussed, but she says that "something as significant I would've recalled".

Mr Scoffield turns to Mrs Hepper's (below) version of events around the 14 June meeting - she said there was "a fulsome discussion around the detail of the figure-work and the two different options" for the RHI scheme.

The then DETI energy boss said she took the CEPA report with her and that those present at the meeting went through tables of the costs to see the differences between the two options.

Image source, RHI Inquiry

Asked for her view, Mrs Foster says: "Given there were no notes of the meeting, it seems that Mrs Hepper has a very clear recollection of all of the issues that were discussed at the meeting.

"I don't have that clear recollection, " Mrs Foster says.

If the costs of the options had all been laid out to her "it would be incredible for me then to sign off a submission that is different to all of that".

Image source, RHI Inquiry

Going against the advice of her civil servants at DETI "would not have been my natural course", says Mrs Foster.

She reiterates her point that she "can't understand why" she would've signed off on going for the ongoing subsidy model for the RHI scheme if she had been give the correct information that it was not the best-value option.

Mrs Foster says in her written evidence that although she has no recollection of the June 2011 meeting, she would have expected DETI's energy boss to highlight "the headline figures" contained in the expert analysis.

The analysis was an economic appraisal prepared by energy experts at the consultancy firm Cambridge Economic Policy Associates.

Image source, Getty Images

Mrs Foster says she thinks Mrs Hepper would have indicated to her which of the two main options for the scheme "was the better value for money, which was going to deliver the most heat on the basis of the economic analysis".

Asked if the expert analysis was explained to her properly, Mrs Foster says: "It obviously wasn't explained to me in those terms otherwise I wouldn't have signed off on submission."

Two main options were on the table for Mrs Foster in relation to the RHI scheme - one type would offer a single up-front grant to applicants; the other would provide ongoing subsidies to claimants over 20 years.

The grants scheme - known as a challenge fund - was rejected because the initial administration costs were £5m while the subsidy scheme cost £1.5m.

The subsidy scheme - which was what was running in Great Britain - was chosen, even though its total cost was £300m higher than the alternative.

Image source, Getty Images

The submission that Mrs Foster received said that an ongoing subsidy scheme was the "preferred approach" and offered the "highest potential renewable heat output at the best value".

That was wrong, though - expert analysis that DETI paid £100,000 for had found that an up-front grants scheme was actually a better option in that regard.

Mrs Foster signed off on the subsidy scheme recommended in the submission but says she wouldn't have done that if she'd known the true cost details behind both options.

Matters begin this morning with a look at a key document and a follow-up meeting in June 2011 that led to the birth of the RHI scheme.

Mrs Foster was sent a ministerial submission by the civil servants working on the RHI scheme for her department, DETI - the document outlined the options and recommendations for the initiative.

Image source, RHI Inquiry

She met the officials - including DETI's energy boss Fiona Hepper - a few days later when they discussed the contents of the submission, but Mrs Foster says she "cannot remember specific details" of the meeting.

Mrs Foster says it's likely that she then made a decision to proceed with one of the options during the meeting.

Image source, RHI Inquiry

Having taken the oath on her first appearance before the inquiry yesterday, Mrs Foster takes her seat and we're straight into the action.

David Scoffield QC, the inquiry's senior counsel, is putting the questions to the former first minister.

If you want to read Mrs Foster's written witness statement, you can find it on the inquiry's website, external.

Mrs Foster was the minister at Stormont's Department of Enterprise, Trade and Investment (DETI) when it set up the RHI scheme in 2012 and in that role she signed off on the project.

A key question for the RHI Inquiry panel will be whether or not she was aware of key information regarding the scheme when she approved it.

Image source, Pacemaker

When the scale of the scandal emerged in December 2016, there were widespread calls for her to resign to allow an investigation to be carried out into what went wrong.

She refused and has consistently denied any wrongdoing in relation to the scheme.

BBC News Northern Ireland

The DUP leader Arlene Foster said she does not think she bears personal responsibility for the collapse of the RHI scheme.

Image source, PA

She made the comments at the start of her evidence to the inquiry and she was glad to have the opportunity to counter "malevolent" and "misinformed" commentary about her role in the debacle.

She added that the fallout had been a matter of "deep regret for me politically and personally".

BBC News Northern Ireland

An independent inquiry into the RHI scandal was established in January last year by the then finance minister Máirtín Ó Muilleoir.

He ordered it in the wake of the huge public concern and what was then a developing political crisis surrounding the scheme.

The RHI Inquiry began in November and Sir Patrick Coghlin (below), a retired Court of Appeal judge, is its chair and has been given full control over how it will operate.

Image source, Pacemaker

It will look at:

• the design and introduction of the RHI scheme
• the scheme's initial operation, administration, promotion and supervision
• the introduction of revised subsidies and a usage cap for new scheme claimants in 2015
• the scheme's closure

For more information on the RHI Inquiry, you can read our handy Q&A.

When the scale of the overspend emerged, public and political concern rocketed.

As the minister in charge of the Stormont department that set up the RHI scheme, the Democratic Unionist Party (DUP) leader Arlene Foster faced calls to resign from her role as Northern Ireland's first minister in December 2016.

Image source, PA

She resisted, and Sinn Féin's Martin McGuinness then quit as deputy first minister in protest at the DUP's handling of what had by then become a full-blown political crisis.

That move brought about the collapse of the Northern Ireland Executive. Now, more than a year on from that, Northern Ireland remains without a devolved administration.

You can find much more detail on the RHI scheme in our need-to-know guide.

The budget of the RHI scheme ran out of control because of critical flaws in the way it was set up.

Claimants could effectively earn more money the more fuel they burned because the subsidies on offer for renewable fuels were far greater than the cost of the fuels themselves.

The most recent estimate for the overspend was set at £700m, if permanent cost controls aren't introduced.

The massive overspend bill will have to be picked up by the Northern Ireland taxpayer.

The Renewable Heat Incentive scheme - or RHI for short - came to the fore of the Northern Ireland public's knowledge in late-2016... and the fallout from the scandal attached to it is still being felt in the region's politics today.

Image source, Getty Images

The scheme was set up by the Northern Ireland Executive in 2012, as a way of encouraging businesses to switch from using fossil fuels to renewable sources for generating their heat.

Those who signed up were offered financial incentives to buy new heating systems and the fuel to run them.

We're almost at the end of a busy week at the Renewable Heat Incentive (RHI) Inquiry but there's still a bit more to hear before we reach the weekend.

Image source, AFP

The Democratic Unionist Party (DUP) leader Arlene Foster gave the first of her evidence yesterday and this morning she's back in the hotseat in the Senate chamber here at Stormont's Parliament Buildings.

We'll have a full live stream of proceedings as well as text commentary of the best bits, so stick with us throughout the day.