Whatever may have happened elsewhere in the workplace, the Catholic Church is not an equal-opportunity employer. The priesthood is still a male preserve, and it follows that to be elected pope, you must be a man.
Over the centuries, a colourful story has grown up about "Pope Joan", a woman said to have disguised herself as a man in order to trick her way into the papacy during the Middle Ages. According to legend, her deception was only discovered when she gave birth to a child.
Despite a widespread belief in this story, all historical research suggests that it is just a myth. But it led to a popular belief that after his election, a new pope had to be "inspected" to make sure he was not a woman. It is thought unlikely that the next pope will have to undergo such an indignity!
The cardinals are unlikely to vote for someone who is nearly 80 - unless they are looking for an interim pope. But equally, they will be reluctant to appoint a young man who could remain in office for 30 years. The ideal age for a would-be pope would therefore appear to be the mid- to late-60s. For a strong candidate this window of opportunity would extend into the early 70s.
But cardinals who once appeared highly electable see their chances diminish rapidly as they approach 80, and younger men establish their reputations. The lengthy papacy of John Paul II has virtually wiped out the chances of a generation of cardinals.
Robust; can cope with long days and international travel
After the brief papacy of John Paul I - he died of a heart attack after just 33 days - anyone with ambitions to become pope has to look healthy. It would be a taxing job for a much younger man - the pope works long hours and is expected to travel widely.
The strain on John Paul II became evident as he crossed time zones and continents to conduct lengthy open-air masses in front of millions. It seems inconceivable that we could return to the days when the pope seldom left the Vatican. So if a candidate has a recent history of illness, there may be doubts about his capacity to meet the physical demands of the job.
The conclave is more likely to elect a candidate from a country that is considered relatively neutral in world politics. For that reason, most Vatican observers believe there is little chance of a pope emerging from the world's one remaining superpower, the US.
But that does not mean that a conclave is not capable of making a political choice. The election of the Polish-born John Paul II, before the great political changes in Eastern Europe, was seen as a message to the Communist world. And the election of a pope from the developing world, at the start of the 21st Century, could be just as significant in its impact on global politics.
Currently the archbishop of a large city, with evidence of good administrative skills; some time at the Vatican an advantage
Experience as a pastor is highly valued. A cardinal who is - or has been - the archbishop of a major city starts with a definite advantage. But the conclave will not want to elect a man who is overwhelmed by the papacy, so they will be looking for other qualities too.
The pope has to combine the spiritual authority of a religious leader with the administrative and diplomatic skills of a head of state who is a player on the international stage. So some experience in the Curia, the Vatican's civil service, may be reassuring to electors.
A man who will become the Church's universal pastor needs to look the part. A saintly demeanour and a reassuring smile is the preferred image today. Popes were once remote figures who rarely ventured beyond the walls of the Vatican.
Now the pontiff is expected to travel the world to show himself to the faithful. He will be visible to a huge international audience on television, so a touch of charisma and some media skills are an advantage.
Traditional views but not extreme - a conservative with a friendly face
As a group, the cardinals are fairly conservative. Most take an orthodox line on controversial issues such as contraception, abortion, the celibacy of the priesthood, and the role of women in the Church. This should not be surprising, as the vast majority were appointed by the conservative-minded John Paul II.
As they meet to choose his successor, the cardinals will be looking for someone they consider sound on doctrine. And while they may want a pope who is less authoritarian than John Paul II, they will be uneasy about electing someone with progressive views who might challenge traditional teaching.
A cardinal needs to be regarded as a safe choice - not too rigid but definitely not a radical. To put it another way, a conservative with a friendly face has the best chance of winning votes.
Wants a less-centralised Church in which bishops have more control
When it comes to electing a pope, there seems to be a definite bias against cardinals who have carved out their careers in Rome. And the perception that the Vatican of John Paul II wielded too much power may count against those cardinals responsible for exercising that authority as part of the Curia - the Church's bureaucracy.
The demand now is for more collegiality - the buzzword for a less centralised Church in which the bishops have a greater say in the way they run their dioceses.
Because most of the cardinals are now bishops or archbishops, it seems reasonable to assume that they will be looking for a pope who recognises this desire for greater power-sharing in the Church.
Fluent in Italian and English, good working knowledge of other languages
Fluent Italian is essential, given the pope's role as Bishop of Rome and the demands of running a Vatican bureaucracy where Italian is the main language. But these days a good working knowledge of English, French and Spanish is very important for a man who heads a global church.
Given the attention that will be focused on him, an ability to put his message across in a variety of languages is a skill that has now become a requirement for the job.
Demonstrates concern for social issues like poverty and unemployment and displays an understanding of the politics of the developing world
Not hobbies or pastimes, even though they may make a cardinal look more human. The conclave will be more concerned with what a cardinal has said and done during his career. An interest in social justice is de rigueur for any candidate who wants demonstrate that he is in touch with the real world.
In countries rich and poor, cardinals have taken a close interest in issues such as poverty, homelessness and unemployment. A campaigning cardinal is more likely to be noticed. But he has to be careful not to stray too far from religion into politics.
The Church in Latin America has been split over the issue of liberation theology, a doctrine that calls for people to be set free from economic oppression. The Vatican has been alarmed by the Marxist overtones. But any candidate hoping to win broad support needs to display a concern for the problems of the developing world, where so many Catholics now live.
Personal contacts with many cardinals, especially in the developing world. Enemies are few - his views do not attract controversy
In the past, many of the cardinals who met in conclave were virtual strangers. Today they travel widely and have many more opportunities to meet on Church business. In this way cardinals can build up a useful network of contacts around the world - particularly useful in the developing world, given its growing importance as a voting bloc.
Being sympathetic to the problems of his colleagues will do a candidate no harm. And avoiding controversy is better than a reputation for being outspoken. A conclave may be a spiritual experience, but church politics can be as fierce as any other kind. Not without reason is it said that the cardinal with fewest enemies is the one who becomes pope.
In most occupations, ambition is considered a good thing. But expressing a desire for the papacy is just not on. Open campaigning is forbidden, and being described by the media as one of the favourites is regarded as a serious handicap.
According to Vatican wisdom, "he who goes into the conclave a pope, comes out a cardinal". This is not entirely true, however, and did not prevent the election of Cardinal Montini, the clear favourite in 1963.
In any event, the choice of a new pope is regarded as the work of the Holy Spirit, rather than base politics. And however much a cardinal may secretly want the job, he has to give the impression that he is being dragged reluctantly to the papal throne.