you'll very likely know if you earn a rating. here's some quick cut and paste information from the usfencing website:
Q.
What is a classification?
A.
A classification is a letter from A to E (with A being the highest) that is earned in competition. The classification reflects the skill level of a fencer. A classification includes the letter assigned as well as the year in which it was last earned, for example "A-02". Classifications are valid for four years, at which point they revert to the next lowest letter, or unclassified, "U", if the classification has not been re-earned within the four year period..
Q.
How can I earn a classification?
A.
You can earn a classification at most USFA sponsored National, Regional, or Local tournaments. USFA sponsored means that the tournament is being conducted by the National Office, a USFA section, or a USFA division.
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relavent link).