Robbie Fowler admits he never looked at his. Paul Gascoigne's reportedly stated he must live close to a fishing lake. And Stefan Schwarz's banned him from travelling into space.

Footballers' contracts are sometimes lucrative, often complex and occasionally bizarre. They can also be at the centre of big disputes between clubs and their players.

So what exactly does a modern footballer's contract look like?

Salaries

Premier League and Football League contracts tend to be quite standard, setting out what is expected from the player and club, and how each is protected.

Matthew Buck is the director of player management at the Professional Footballers' Association. He explains: "A contract will include a basic salary, signing-on fees, loyalty fees, objectives based on games, sub-agreements for image rights and any clauses you may wish to negotiate."

Analysis Mark Lawrenson BBC football analyst and former Liverpool defender When I was playing, a contract was probably three, four, five pages long and they were mostly immaterial. I looked to make sure the figures were right and would not necessarily have read all the small print. Nowadays the contracts are more like a John Grisham novel, with so many different clauses in them, including image rights, how they are insured, the whole works. Lots has changed but there are still some things which are relevant today, including loyalty payments. If you had a five-year contract and you were sold after three, you would still get your loyalty money as long as you did not ask for a transfer. That means, financially, you can be better off if you are a failure on a regular basis because managers will often make it as lucrative as possible for you to leave.

Top earners in the Premier League can receive a salary of up to £250,000 a week, according to Buck, but the average wage in England's top flight is about £25,000 to £30,000 a week.

That drops to an average of £1,300 to £1,500 a week in the fourth tier - League Two.

The Financial Fair Play regulations recently introduced by European governing body Uefa mean many clubs now prefer to tailor contracts towards performance-related earnings, rather just than a basic salary.

This is especially the case when a player is still trying to prove himself or reaching the twilight of his career. Those at their peak are in a stronger position to negotiate a bigger basic package.

Even clubs like 2012 Premier League champions Manchester City have structured salaries in player contracts.

In his book Goal, Manchester City chief executive Ferran Soriano says he usually aims to "pay two-thirds fixed salary and one-third variable based on the success of the team and a player playing at least 60% of first-team matches".

Appearance-based deals can have their drawbacks for players though. Preston striker Kevin Davies, who spent 15 seasons in the Premier League, says: "I know players who have got within a game of earning a new deal. Then, depending on the club's finances or a new manager who doesn't fancy them, it turns out they don't play again."

So the PFA advises that players should only look at a contract in terms of what is guaranteed income.

If you are a confident player on the way up, it can make sense to take a more risky long-term view.

Football agent Sky Andrew, who represents players in the Premier League, says: "Sometimes it makes sense to push for 10% of your sell-on fee rather than another £1,000 a week."

Bumper bonuses

There are a swathe of bonuses that players can earn.

A 30-second substitute appearance could be worth as much as £5,000. Bonuses for goals, assists or clean sheets can bring the same reward.

Average salaries Premier League: £25,000 to £30,000 a week. Top earners: £250,000

Championship: £4,000 to £5,000 a week. Top earners £8,000 to £9,000

League One: £1,700 to £2,500 a week

League Two: £1,300 to £1,500 a week Source: PFA

In Major League Soccer in the United States, players are even paid for second assists - the pass that leads to an assist. Incentives are also paid based on a team's league position, which could be a pot worth as much as £5m, split among the whole squad.

That can become even more lucrative for Champions League qualification.

Davies insists the fortunes of his team were always more important to him than individual bonuses, but he adds: "I know some players who have come in on high goal bonuses and it's no surprise when they are shooting from all over the place."

According to sports lawyer Liz Ellen, who works for London law firm Mishcon de Reya, personalised targets are becoming less common at top Premier League clubs.

"A lot of clubs won't do goal or assist bonuses because it makes the player less self-assured and less focused on the team," she said.

Weird and wonderful

Former Sunderland midfielder Stefan Schwarz let slip that he might like to travel into space after joining the Black Cats in 1999, so the club inserted a clause banning the Swede from space travel.

Former Crystal Palace chairman Simon Jordan claims Neil Ruddock had a clause in his contract stipulating that his earnings would be reduced if he was found to be overweight.

Image rights Are owned by a player

They allow him to exploit his value in a similar way to a commercial brand like Adidas or Lucozade

A player can apportion some of these rights to a club as part of their contract, allowing the employer to use his image to help sell tickets, shirts or other products and services

They allow a player to receive a portion of the revenue generated from the use of his image

Image rights deals generally account for 10 to 25% of a player's contract

Earnings can be paid into a player's image rights company, thereby avoiding some tax

More common clauses range from increased earnings if a player gets an international call-up to free rent at an apartment or house.

Buyout clauses have recently been in the news. Marouane Fellaini had a £23.5m release clause in his contract with Everton which expired on 31 July, yet Manchester United still paid £27.5m for him on deadline day.

Arsenal bid £40,000,001 for Luis Suarez, after they got wind of a clause requiring that Liverpool must consider offers over £40m for the striker. In the end the Anfield club said the Uruguayan was not for sale anyway and he stayed.

Andrew believes buyout clauses should be included in contracts, as they benefit all parties if a player does well. Yet Buck argues "it could restrict transfer activity" if a player struggles.

Image rights tend to be limited to the top end of the Premier League and have become less common as the tax man has clamped down on those using them to circumvent UK tax laws.

Now they are used for genuine commercial purposes and can account for roughly 10 to 25% of a player's contract.

Ellen says: "If, for example, a company came in and said 'we will sponsor you £5m a year if you have this particular player', then you can see that paying the player a high percentage for his image rights makes commercial sense."

Foreign players are able to gain further benefits. Until they have lived in the UK for three years, they only need to pay the tax equivalent to the amount of time they have spent here.

Disputes

"The biggest contractual issue comes when a perceived bigger club comes in for a player, or a player is aware of the interest via an agent or the media," says Buck, who is also a licensed agent.

"Players want to better themselves but the PFA encourages players to always honour their contracts because we expect clubs to do the same."

Tevez was in dispute with Manchester CIty during the 2011-12 season

Andrew adds: "There is a perception that players have the power, but what the Suarez scenario showed is that if a player is under contract then he has to honour it.

"For every player who says he doesn't want to play for a club, you have a hundred players who are released by their clubs. The true situation is that there are very few players who find themselves in positions of power at the top level."

PFA regulations ensure that if a player does cross the boundaries of accepted behaviour, initially they can only be fined a maximum of two weeks' wages.

But that can still amount to plenty in Carlos Tevez's case. He was fined an initial £400,000 after allegedly refusing to play for Manchester City against Bayern Munich.

If things remain cordial and a player does leave, he would tend to waive his basic salary for the rest of his contract but would be paid any signing-on or loyalty fees due.

Buck says: "Even with disputes I've had with players and clubs trying to agree a fee, for the most part it's quite calm.

"There is a probably a bit of brinkmanship toward the end of a contract but the clubs are working as a business and they want to get the best value they can."