Reigning NFL MVP Lamar Jackson is challenging Pro Football Hall of Fame quarterback Troy Aikman's use of their shared No. 8 in a U.S. Patent and Trademark Office complaint, according to federal records.

Jackson, who owns or has applied for several trademarks using the number in various phrases, says Aikman's attempt to use "EIGHT" on apparel and bags would be "likely to cause confusion, or cause mistake, or to deceive" the purchasing public as to whether they're buying products from Jackson or Aikman's company, Jackson's attorney said in July 9 filings.

Jackson "has expended considerable time, effort, and expense in promoting, advertising, and popularizing the number 8 in connection with his personality and fame" and "is well-known by this number due to his notoriety and fame, along with his promotion of this number in his trademarks and in media coverage," according to the appeals.

The Baltimore Ravens quarterback, through his attorney, has filed two appeals to the trademark office against FL101, a company that lists Aikman as one of its directors in SEC filings, targeting its use of "Eight" on apparel and bags. FL101 is listed as the owner of nine trademark applications for the use of "Eight" on a variety of consumer products, including beer, beach towels and energy drinks.

Messages left with FL101's attorneys were not immediately returned to ESPN. Jackson's attorney did not immediately respond to questions sent by ESPN to her email.

Jackson and Aikman wore the No. 8 for the entirety of their professional careers. Aikman wore No. 8 in college at UCLA and Jackson wore the number at Louisville. Aikman played 12 seasons as the Dallas Cowboys' quarterback and is now a Monday Night Football analyst for ESPN.

Jackson has applied for trademarks on multiple usages of the number eight, including "Era 8 by Lamar Jackson," "Era 8," "You 8 yet?" and a logo of a "stylized wild dog" over a shield with "2018 Era 8 by Lamar Jackson 2018" around the dog. Jackson's attorney says his trademarks of these sayings using the number were registered before Aikman's "Eight" and that the products from Aikman's company are "highly similar in sound, appearance, connotation, and commercial impression" to Jackson's trademarks.

"Some of the instant reaction is, like, how can you own a number?" Christine Farley, a law professor and intellectual property expert at American University, said. "The truth is you can own almost anything you think of as a trademark.

"You can own a smell. You can own a sound. You can own a single color. You can own a single number."

A trademark's look can make a difference in a filing and an appeal, Farley said, and there are different categories of use. The USPTO has 9,996 live registered or pending trademarks including the word "eight" and 1,801 live registered or pending trademarks containing the numeral "8," according to its database.

Farley said the attorneys for Aikman's company might argue consumers would not be confused by the presence of a number when it comes to purchasing a product. A response from FL101 is due to the federal trademark office by Aug. 18, according to federal records.

Jackson and Aikman are not the only famous No. 8s. In football, Hall of Fame quarterback Steve Young also wore the digit. In other sports, Hall of Fame baseball players Cal Ripken Jr., Yogi Berra and Carl Yastrzemski along with basketball Hall of Famers Kobe Bryant and Walt Bellamy had the number on their jerseys, as has Washington Capitals star Alex Ovechkin.