USA Fencing classifies fencers with letter ratings: A (highest), then B, C, D, E, and U for unrated. They're written with the year earned, "A24" means an A earned in 2024.
There's no test and no minimum experience, you earn ratings by placing well at tournaments, like winning a prize. What rating an event can award depends on how many fencers enter and how strong they are, so a rating is really a measure of who you've beaten. An A can take years, sometimes a decade, to earn.
Ratings mostly exist to seed tournaments fairly. Chasing letters is fun, but the real goal is improving, the rating follows. Next: the pathway to elite and Olympic fencing.