When people purchase plane tickets, they have to select a "gender" option: male or female. But those two categories don’t cover everyone, so some major airlines are planning to offer more choices.

Airlines for America and the International Air Transport Association, two trade groups that represent major air carriers, recently approved a measure that will let their member airlines add "unspecified" and "undisclosed" as identification options. That way, the airlines’ systems could align with recent changes in some states and countries that allow people to designate their gender as X rather than M or F on government IDs.

The measure, first reported by the Daily Beast, goes into effect June 1. Each airline will be able to decide whether and when to change its own system.

American Airlines is already working on adding the nonbinary option, although it’s unclear when that will be complete, a representative for the carrier said Friday. Other airlines making the change include Delta, United, and Alaska Airlines, according to the Daily Beast.

U.S. airlines are required to collect name and gender information, though the Transportation Security Administration doesn’t have an official policy on processing IDs with gender-neutral markers. California, Oregon, Colorado, Arkansas, Minnesota, and the District of Columbia offer a nonbinary gender marker — X — on driver’s licenses and identification cards.

Beck Bailey, deputy director of the Human Rights Campaign’s Workplace Equality Program, called the airline trade groups’ decision "a necessary shift."

In addition to recognizing the reality of nonbinary people and making them feel represented, Bailey said, the decision could pave the way for greater privacy options. As a society, we "tend to ask for data we don’t really need. A lot of times we ask for a person’s gender and don’t necessarily need that piece of information," he said.

The airline trade groups did not describe how they decided to make the change or why it’s happening now. The International Air Transport Association said in a statement that it acted "at the direction of" its members.

Airlines for America emailed a statement saying: “U.S. airlines value a culture of diversity and inclusion, both in the workplace and for our passengers, and we work hard each day to accommodate the needs of all travelers, while delivering a safe, secure and enjoyable flight experience.”