Protected rankings allow tennis players to return to major tournaments following time away from the sport, usually because of injury.

They are used by top-performing players to enter the main draw or qualifying competition of Grand Slams and other tournaments if their ranking has dropped too low during their time off for them to be automatically eligible.

Entry to the main draw of Grand Slams is determined by world rankings, with a cutoff around number 100. Protected rankings allow players who have fallen beyond this cutoff to enter directly through the main draw.

Protected rankings cannot be used to obtain a seeding, meaning that players entering Grand Slams this way may face top players earlier in the tournament.

Players can petition the ATP or WTA (the governing bodies for men’s and women’s tennis respectively) for a protected ranking when they have been absent from any tennis events for at least six months because of a physical injury.

Women who are making a comeback to tennis after maternity leave are also eligible.

On the men’s side, a protected ranking is calculated using the player’s average ranking over three months following their injury. They can use this ranking for the first nine tournaments or months following their comeback – whichever comes first. But if the player is out for more than a year, this is extended to 12 tournaments/months.

On the women’s side, their ranking stays the same as it was at the time of injury. They can use this ranking for eight tournaments in a single season, or 12 tournaments if they miss more than one year.

This article is the latest from BBC Sport’s Ask Me Anything team.