Sen. Kamala Harris has chosen "Pioneer" as her Secret Service code name nearly a week after being chosen as the presumptive Democratic vice presidential nominee, reports CNN.

Politicians and family members under Secret Service protection choose their own code names, often as a play on certain characteristics. 

Secret Service protection for Harris began last week after Joe Biden chose her as his running mate. The names are picked from a list of approved options from the White House Communications Agency. 

Harris' chosen code name is a small nod to the historic nature of her selection, according to CNN. She is the first Black woman and Indian American woman to appear on a major party ticket, and if the duo wins in November, she'll continue to earn a number of firsts.

Upon an electoral win, in addition to being the first female vice president, Harris would be the first Indian American vice president, the first Black vice president and the first Jamaican American vice president.

According to HuffPost, the presumptive Democratic presidential nominee will keep his code name "Celtic" that he had for eight years as vice president to former President Barack Obama. 

Barack's code name was "Renegade," and Michelle, Malia and Sasha Obama were called “Renaissance,” “Radiance” and “Rosebud” respectively. 

It has not been revealed yet what Secret Service agents will call Harris' husband Douglas Emhoff, but Biden's wife Jill will keep her old code name of “Capri.”

President Donald Trump made his Secret Service name "Mogul," CNN reported in 2016. Last year Quartz gained access to government filings that also had the code names for Melania, Donald Jr., Ivanka and Eric Trump, who gave themselves the names “Muse,” “Mountaineer," Marvel” and “Marksman” respectively.

CNN also reported in 2016 that Vice President Mike Pence and his wife Karen go by "Hoosier" and "Hummingbird."

"Over time, the (Secret Service) protectees have almost taken on the persona of the call sign that they had selected. With (former President Barack) Obama, 'Renegade' is a great example: how he went against the establishment in some of the things that he had done, and like Barbara Bush, whose call sign was 'Tranquility,' embodied the tranquility and peacefulness in a time of war," Jonathan Wackrow, a former Secret Service special agent, told CNN.

CNN noted that vice presidents typically keep Secret Service protection for up to six months after they leave office. According to The Guardian, code names have routinely been leaked to the press since the practice of assigning names was started after World War II.

Code names were originally assigned for security, but now it has become a tradition. Families all have code names that start with the same letter, CNN reported.