The requirements in this subpart apply to for-hire motor carriers, employers, officers and persons registered or required to be registered under 49 U.S.C. § 13902, 49 CFR part 365, and 49 CFR part 368. When used in this subpart, the term “motor carrier” includes all for-hire motor carriers, employers, officers and other persons, however designated, that are registered or required to be registered under 49 U.S.C. § 13902, 49 CFR part 365, and 49 CFR part 368.