Everyone who joins USPC will be awarded skill Certificates beginning at the D1 level and progressing through D2, D3, C1 and C2 at the club level. USPC changed its terminology a few years ago from "Ratings" to "Certificates" but you may still hear people use the words interchangeably. The H-B, C-3, B, H/H-A, and A are administered by the USPC National Testing Committee at testings scheduled though the National Office. Applications for National Level tests are submitted through the USPC website.
During a test, whether done at the local or national level, members' skills and knowledge are tested against the Standards of Proficiency which outline the expectations to be met at each level in each section - Horse Management, Riding on Flat and Riding Over Fences.
Another fairly new change to testings at all levels is the ability to take the test in Horse Management, Riding on the Flat and Riding over fences at different times. In addition, members may now take specialty certifications in certain disciplines as they progress up the ladder.
DCs and CAs strive to provide testing opportunities to their members in a timely manner when desired. Clubs and Centers typically hold testings two to four times a year or possibly even more. Many DCs/CAs will allow their members to participate in testings being offered by another club or center if a member wishes to test sooner than or has a conflict with the date of the next scheduled testing within their own club or center. However, no member is allowed to test with another club or center without the permission and support of their DC/CA.
USPC provides an excellent Chart of Learning on their Club/Center Level Testing Materials page.