Article 18
Counterfeit postage stamps
The high contracting parties undertake to adopt, or to propose to their respective legislatures, the necessary measures for punishing the fraudulent use of counterfeit postage stamps or stamps already used for the prepayment of correspondence. They also undertake to adopt, or to propose to their respective legislatures, the necessary measures for prohibiting and repressing the fraudulent manufacture, sale, offering for sale, or distribution of embossed and adhesive stamps in use in the postal service, forged or imitated in such a manner as to be mistakable for the embossed and adhesive stamps issued by the Administration of any one of the contracting countries.
Article 19
Special arrangements for particular services
The services concerning letters and boxes of declared value, postal money orders, postal parcels, collection of bills and drafts, certificates of identity, subscriptions to newspapers, etc., form the subject of special arrangements between the various countries or groups of countries composing the Union.
Article 20
Regulations of Execution; special agreement between Administrations
1. The Postal Administrations of the various countries composing the Union are competent to draw up, by common consent, in the form of Regulations of Execution, all the measures of order and detail which are judged necessary.
2. The several Administrations may, moreover, make amongst themselves the necessary arrangements on the subject of questions which do not concern the Union generally, provided that those arrangements do not derogate from the present Convention.
3. The Administrations concerned are, however, permitted to come to mutual arrangements for the adoption of lower rates of postage within a radius of 30 kilometres.
Article 21
Internal laws; restricted unions
1. The present Convention does not involve alteration in the legislation of any country as regards anything which is not provided for by the stipulations contained in this Convention.
2. It does not restrict the right of the contracting parties to maintain and to conclude treaties, as well as to maintain and establish more restricted Unions, with a view to the reduction of postage rates or to any other improvement of postal relations.
