Officers of the Foreign Service shall charge for official services performed abroad at the rates prescribed in this schedule, in coin of the United States or at its representative value in exchange (22 U.S.C. 1202). For definition of representative value in exchange, see § 23.4 of this chapter. No fees named in this schedule shall be charged or collected for the official services to American vessels and seamen (22 U.S.C. 1186). The term “American vessels” is defined to exclude, for the purposes of this schedule, undocumented American vessels and the fees prescribed herein shall be charged and collected for such undocumented vessels. However, the fees prescribed herein shall not be charged or collected for American public vessels, which includes any vessel owned or operated by a U.S. Government department or agency and engaged exclusively in official business on a non-commercial basis. This schedule of fees shall be kept posted in a conspicuous place in each Foreign Service consular office, subject to the examination by all persons interested therein (22 U.S.C. 1197).