rates determined by the various Articles of the present Convention. Such countries have the option of rounding fractions in conformity with the table inserted in the Detailed Regulations mentioned in Article 20 of the present Convention.
The Administrations which maintain post offices forming part of the Union in non-Union countries fix their rates in the local currency, in the same manner. When two or several Administrations maintain such offices in the same non-Union country, the local equivalents to be adopted by all such offices are fixed by mutual arrangement between the Administrations concerned.
Article 11
Prepayment; reply coupons; exemptions from postage
1. Prepayment of postage on every description of article can be effected only by means of postage stamps valid in the country of origin for the correspondence of private individuals. It is not, however, permitted to make use, in the international service, of postage stamps produced with an object special and peculiar to the country of issue, such as the so-called commemorative postage stamps of temporary validity.
Reply post cards bearing postage stamps of the country in which these cards were issued are considered as duly prepaid, as also are newspapers or packets of newspapers without postage stamps but with the superscription "Abonnements-poste" (subscription by mail), which are sent in virtue of the Special Arrangement for newspaper subscriptions, provided for in Article 19 of the present Convention.
2. Reply coupons can be exchanged between the countries of which the Administrations have agreed to participate in such exchange. The minimum selling price of a reply coupon is 28 centimes, or the equivalent of this sum in the money of the country which sells it.
This coupon is exchangeable in all countries parties to the arrangement for a postage stamp of 25 centimes or the equivalent of that sum in the money of the country where the exchange is requested. The Detailed Regulations contemplated in Article 20 of the Convention determine the other conditions of this exchange, and in particular the intervention of the International Bureau in manufacturing, supplying, and accounting for the coupons.
3. Official correspondence relative to the Postal Service exchanged between Postal Administrations, between these Administrations and the International Bureau, and between Post Offices in Union countries, is exempt from prepayment by means of ordinary postage stamps, and is free from liability to charge.
4. The same privilege is accorded to correspondence concerning prisoners of war, despatched or received, either directly or, as intermediary, by the special Information Offices established on behalf of such persons in bellig-
