You may not know how it works, but a law-making process that has existed for less than four years will be scrapped if Wales votes Yes in the referendum next Thursday, 3 March. BBC Wales political reporter Daniel Davies explains.
Fire sprinklers are to be compulsory in new homes thanks to a piece of legislation nodded through the Welsh assembly this month.
It makes Wales the first country where sprinkler systems will have to be fitted by law in all new houses, student halls, old people's homes and apartment blocks.
It had unanimous support from AMs but took three-and-a-half years to get through the assembly.
It was proposed by Labour backbencher Ann Jones in July 2007 and came about due to a system of orders that allow the assembly to notch up more law-making powers.
Introduced after the last election, legislative competence orders (LCOs) are a way for the assembly to request transfers of power from parliament in devolved policy fields on a case-by-case basis.
Only when an LCO has been approved can the assembly pass laws. So after winning a ballot of AMs, Ms Jones had to first seek the Westminster parliament's approval for an LCO before beginning the work of legislating to get her idea on the statute book.
Since their inception, 16 LCOs have been approved, but not all have passed smoothly. An attempt to obtain powers over affordable housing was batted back and forth between Cardiff and Westminster for nearly three years.
A Yes vote would consign LCOs to history and grant the assembly primary law-making powers in the 20 devolved policy fields.
'Make legislation better'
Critics complain the system is long-winded and complicated. But that is true of any law-making system, said David Davies, the Conservative MP for Monmouth, who will vote No in the referendum.
Mr Davies, chairman of Westminster's Welsh affairs committee, said: "Legislation is a complicated businesses. If you get any piece of legislation and read it through you would find it's complicated.
"It's actually not that complicated if you are interested in how legislation is passed.
"The truth is the vast majority of people are not interested in the technicalities - and I don't blame them."
Although he opposed the act which created LCOs and which opened the door to the referendum, Mr Davies said AMs and MPs have acted well together to make the system work.
"It doesn't make for such a good story that the first minister and the chairman of the Welsh affairs committee had a nice cup of tea and a good chat," he said.
He compared Westminster's role in the LCO system to the relationship between the House of Lords and House of Commons.
"What you're actually doing is increasing the number of people who can help you make legislation better."
But not everyone's experience is so positive.
Vale of Clwyd AM Ms Jones said lives could have been saved if her legislation had received a speedier passage through the assembly.
At one stage she feared all her efforts would have been for nothing if a general election was called before her LCO was passed.
"That's why I have come out for a Yes vote - because all of that hard work would have been lost."
She added: "The politicians were great. But it was the Whitehall bit, the civil service bit, that really dragged it all out.
"Every stage that we went through was a major stage.
"You just keep pushing and pushing. I would have liked it to have gone through sooner."