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A new chapter in the Scottish independence referendum story is about to be written - because we've now entered into the official campaign period.

Voters north of the border will go to the polls on 18 September when they will be asked the "Yes/No" question: "Should Scotland be an independent country?"

They've got about 16 weeks to listen, watch and read all the arguments - from both sides of the campaign - in order to make up their minds.

But what is this campaign period all about? Here's everything you would want to know....

What is the referendum period?

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It's a timeframe in the run up to the 18 September vote itself to ensure the campaign is fought fairly, and aims to provide a level playing field when it comes to issues like spending. It has been set out in the Scottish government's Referendum Act, which contains the rules for the campaign.

Why 16 weeks?

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This has roots in the last big referendum seen in the UK - the 2011 poll on changing the way MPs are elected. In its post-AV referendum report, the Electoral Commission recommended the 10-week period be increased to at least 16 weeks, to allow more time for the main campaigns to put their arguments to voters. This 16-week period is also in line with the campaign spending period for Scottish Parliament elections. And it's not to be confused with the referendum "purdah period", which prevents government from announcing new legislation. That begins on 21 August.

Spending limits

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Anyone can splash up to £10,000 on campaigning during the referendum period. Any more, though, and they need to register with the Electoral Commission watchdog. The main opposing campaigns for independence and the Union - Yes Scotland and Better Together - each get to spend £1.5m during the referendum period, under their "lead campaigner" status. They also get free stuff, like a voter mailshot and complimentary use of certain public spaces. In terms of political parties, the SNP is allowed to spend £1,344,000 while the Greens - Holyrood's other pro-independence party - have a £150,000 limit. Scottish Labour gets to spend £831,000, the Scottish Conservatives £399,000 and the Scottish Liberal Democrats, £204,000. Media playback is unsupported on your device Media caption What are the referendum campaigns all about? We explain.

Rule breaking

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Exceeding a spending limit is a criminal offence and the Electoral Commission has powers to impose civil sanctions. The Crown Office - Scotland's criminal prosecution service - can also prosecute offences through the courts. Campaign material is subject to the usual laws which cover things like defamation, copyright and intention to stir up racial hatred. The Electoral Commission doesn't regulate campaign material. The police are responsible for investigating alleged offences, while defamation issues are a matter for the civil courts. Media playback is unsupported on your device Media caption What is the Electoral Commission's role in the referendum?

Who can campaign?

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Members of the public can search for registered campaigners through the Electoral Commission. The rules allow a wide variety of official campaigners, from individuals to groups, companies and trade unions - as long as they're registered in the UK.

Deadlines, deadlines, deadlines

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Campaigners need to send monthly donation and loan reports to the Electoral Commission, the first of these due on Tuesday 8 July. Those who have spent £250,000 or less need to send in their spending returns by 18 December 2014, while those which have spent more than that get until 18 March, next year. And remember, if you want to vote in the referendum, you must be registered by midnight on 2 September. The application deadline for a postal or proxy vote is 17:00 the next day.

Press rules

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News reports, features and editorials in print or online media are not subject to electoral law, says the Electoral Commission. Broadcasters must stick to rules on impartiality and guidelines on how to achieve this have been published by both the BBC and regulator Ofcom.

Referendum re-run?

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