(a) There are four types of rate adjustments for market dominant products. A Type 1–A rate adjustment is authorized under 39 U.S.C. 3622(d)(1)(D). A Type 1–B rate adjustment is authorized under 39 U.S.C. 3622(d)(2)(C). A Type 2 rate adjustment is authorized under 39 U.S.C. 3622(c)(10). A Type 3 rate adjustment is authorized under 39 U.S.C. 3622(d)(1)(E).