(a) Statement in United States currency required. All fares and charges shall be stated in cents or dollars of the United States except as provided in paragraph (b) of this section.

(b) Statements in both United States and foreign currencies permitted. Fares and charges applying between points in the United States, on the one hand, and points in foreign countries, on the other hand, or applying between points in foreign countries, may also be stated in the currencies of foreign countries in addition to being stated in United States currency as required by paragraph (a) of this section: Provided, that:

(1) The fares and charges stated in currencies of countries other than the United States are substantially equivalent in value to the respective fares and charges stated in cents or dollars of the United States.

(2) Each record containing fares and charges shall clearly indicate the respective currencies in which the fares and charges thereon are stated, and

(3) The fares and charges stated in cents or dollars of the United States are published separately from those stated in currencies of other countries. This shall be done in a systematic manner and the fares and charges in the respective currencies shall be published in separate records.

(a) Specific points of origin and destination. Except as otherwise provided in this part, the specific points of origin and destination from and to which the fares apply shall be specifically named directly in connection with the respective fares.

(b) Directional application. A tariff shall specifically indicate directly in connection with the fares therein whether they apply “from” and “to” or “between” the points named. Where the fares apply in one direction, the terms “From” and “To” shall be shown in connection with the point of origin and point of destination, respectively, and, where the fares apply in both directions between the points, the terms “Between” and “And” shall be shown in connection with the respective points.

Tariffs shall specify whether or not the fares therein include services in addition to airport-to-airport transportation.

(a) Definite application. Add-on fares shall be specifically designated as “add-on” fares on each page where they appear.

(b) A tariff may provide that fares from (or to) particular points shall be determined by the addition of add-ons to, or the deduction of add-ons from, fares therein which apply from (or to) a base point. Provisions for the addition or deduction of such add-ons shall be shown either directly in connection with the fare applying to or from the base point or in a separate provision which shall specifically name the base point. The tariff shall clearly and definitely state the manner in which such add-ons shall be applied.

(c) Restrictions upon beyond points or connecting carriers. If an add-on fare is intended for use only on traffic originating at and/or destined to particular beyond points or is to apply only in connection with particular connecting carriers, such application shall be clearly and explicitly stated directly in connection with such add-on fare.

(a) Fares for foreign air transportation of persons or property shall not be stated in the form of percentages, multiples, fractions, or other relationships to other fares except to the extent authorized in paragraphs (b), (c), and (d) of this section with respect to passenger fares and baggage charges.

(b) A basis of fares for refund purposes may be stated, by rule, in the form of percentages of other fares.

(c) Transportation rates for the portion of passengers' baggage in excess of the baggage allowance under the applicable fares may be stated, by rule, as percentages of fares.

(d) Children's, infants' and senior citizen's fares, may be stated, by rule, as percentages of other fares published specifically in dollars and cents (hereinafter referred to as base fares): Provided, that:

(1) Fares stated as percentages of base fares shall apply from and to the same points, via the same routes, and for the same class of service and same type of aircraft to which the applicable base fares apply, and shall apply to all such base fares in a fares tariff.

(2) Fares shall not be stated as percentages of base fares for the purpose of establishing fares applying from and to points, or via routes, or on types of aircraft, or for classes of service different from the points, routes, types of aircraft, or classes of service to which the base fares are applicable.

The publication of fares or charges of a carrier which duplicate or conflict with the fares of the same carrier published in the same or any other tariff for application over the same route or routes is hereby prohibited.

Where no applicable local or joint fare is provided from point of origin to point of destination over the route of movement, whichever combination of applicable fares provided over the route of movement produces the lowest charge shall be applicable, except that a carrier may provide explicitly that a fare cannot be used in any combination or in a combination on particular traffic or under specified conditions, provided another combination is available.