The school admissions system says "fairness" is the priority.
When it comes to school admissions everyone says they want a fair system.
But what does this mean? When more families want to send their children to a school than there are places, what is a fair way of giving priority?
Living near a school, an admissions lottery, creating a mix of abilities, religious affiliation, passing an exam... these are all used in secondary schools in England to decide the allocation of places.
Each will mean winners and losers. How can an admissions system promote both choice and fairness?
LIVING NEAR THE SCHOOL
Living near the school is one of the most common ways of determining priority when a school is oversubscribed.
This is often called the "proximity" rule - even though the word does not appear anywhere in the current admissions code.
This code describes the distance between home and school as a "clear and objective oversubscription criterion".
In its favour, the government says there is a benefit in reducing travelling time for children.
But does that make it fair? If you live next door to a school with terrible results and the distance ruling puts good schools out of reach, it might not seem very fair at all and might seem like a social barrier.
In terms of "fairness", it is a tough balancing act. On the one hand, it might seem fair that a pupil living close to a school should be able to go there.
But on the other, it lets the wealthy queue-jump by buying into the vicinity of a good school. Why should parents' being able to afford a property bring greater priority in a child's access to a public service?
In a bid to tackle the pattern of affluent families buying up houses surrounding the most successful schools, a growing number of authorities have been using a system called "fair banding".
The principle is that schools will take in pupils from a wider area, with places given in a way that will create a spread of pupils with a range of abilities.
On the fairness side of the balance sheet, this means that a wider social mix will have access to schools which otherwise would remain the preserve of wealthier households. It moderates the way that using distance can confine the poorest families to the lowest-achieving schools.
However, the devil can still be in the detail. Based on primary school banding tests, schools allocate a proportion of places to each ability band. But this can be based not on the spread of ability across the local neighbourhood, or the local authority or national averages - but only on those applying to an individual school.
So if a large proportion of the applicants to a sought-after, highly successful school are in the top ability band - then the allocation of places can reflect this.
The idea of using a lottery - or "random allocation" - is to remove all possible social advantages. It is indifferent to address, ability or religion. Luck determines who is given a place.
This certainly removes inequality. But it could create some anomalies. A child living beside a school could be sent on a huge journey to the other side of town. Brothers and sisters could end up in different schools. Twins could be separated.
Schools Secretary Ed Balls has delivered an icy blast on the use of lotteries, suggesting that parents do not like the uncertainty and lack of control. It works against all the promises to give parents more choice.
In contrast the admissions code, introduced this year, speaks warmly of lotteries, saying they can be "good practice".
"Random allocation can widen access to schools for those unable to afford to buy houses near to favoured schools and create greater social equity," says the code.
In pursuit of fairness for the most vulnerable, the admissions process operates a kind of priority boarding system for groups of children seen as being in need of greatest support.
Children in local authority care are at the top of this list.
"All admission authorities must give highest priority in their oversubscription criteria to these children," says the code.
Children with special educational needs also have to be considered as a priority.
Faith schools have to follow the admissions code, but as an additional tie-breaker can give higher priority to pupils who adhere to a particular religion.
This raises the question as to how this is defined when there are more applicants than there are places.
The admissions rules pass the question back to the faith schools. "It is for the relevant faith provider group or religious authority to decide how membership or practice is to be demonstrated."
This can mean receiving a letter from a church or religious group to say a child attends services or provide other evidence of a commitment to a religion.
Where there is great pressure on places in very popular faith schools, the more demanding such proofs of religious commitment can become.
In terms of "fairness", faith schools are an example of how fairness is in the eye of the beholder.
Parents wanting to exercise their right to a choice of schools will say it is entirely fair that they should be able to send their child to their preferred faith school. It is not their fault if such schools are too popular.
On the other hand, opponents of faith schools say how can it be fair that a child is denied a place at a state school because they do not follow a particular religious belief?
It is an example of how difficult it is to reconcile the expectation of choice and the reality of rationing.
TESTS AND APTITUDE
There are still 164 grammar schools in England, where entry is determined by a test.
In terms of fairness, grammars have been championed as a way of allowing bright children from poor homes to get into high quality academic schools.
The 11-plus exam once decided the fate of school admissions
On the debit side, the use of tutors to coach pupils through the 11-plus has meant that grammars have been seen as being dominated by the middle classes.
There is also an argument that selection by ability is inherently unfair as it penalises those who cannot pass an arbitrary test.
However a growing number of state schools, particularly academies, are using "aptitude" as a way of allocating a proportion of places. This might mean taking a test in a subject such as music.
What is the difference between selection by "aptitude" and selection by "ability"?
"A child with aptitude is one who is identified as being able to benefit from teaching in a specific subject, or who demonstrates a particular capacity to succeed in that subject," says the code.
Again, this highlights the different ways that fairness can be interpreted.
Aptitude tests clearly involve an element of selection - but the rules see this as fair competition, in the pursuit of giving children the most suitable school.
But ability tests, apart from in existing grammars, are seen as an unfair competition and are disallowed.
While the aim of the admissions code is fairness, there are other traditional practices that cut across this.
One of the most common methods of giving priority is for the brothers and sisters of pupils at the school.
This is convenient for travel and, if they like the school, it is reassuring for families.
But in the battle for places, it can be a wildcard in reducing the availability of places for eldest children with no siblings to follow.
When schools can use a combination of any or all the above systems - banding, distance, aptitude and lottery - the block of places occupied by siblings can either feel like a welcome back door or an unfair narrowing of the entrance.
WHAT IS NOT ALLOWED
The admissions rules are designed to deter schools from using surreptitious methods of selecting pupils.
Interviews are not allowed, schools cannot check whether applicants will make financial donations or ask personal questions about a child's family background.