Artikel 155

1. In the documentation published by the Union, the French, English, Arabic and Spanish languages shall be used. The Chinese, German, Portuguese and Russian languages shall also be used, provided that only the most important basic documentation is produced in these languages. Other languages may also be used on condition that the member countries which have made the request bear all of the costs involved.
2. The member country or countries which have requested the use of a language other than the official language constitute a language group.
3. Documentation shall be published by the International Bureau in the official language and in the languages of the other duly constituted language groups, either directly or through the intermediary of the regional offices of those groups in conformity with the procedures agreed with the International Bureau. Publication in the different languages shall be effected in accordance with a common standard.
4. Documentation published directly by the International Bureau shall, as far as possible, be distributed simultaneously in the different languages requested.
5. Correspondence between the member countries or their designated operators of member countries and the International Bureau and between the latter and outside entities may be exchanged in any language for which the International Bureau has available a translation service.
6. The costs of translation into any language, including those resulting from the application of paragraph 5 and article 136, shall be borne by the language group which has asked for that language. The member countries using the official language shall pay, in respect of the translation of non-official documents, a lump sum contribution, the amount of which per contribution unit shall be the same as that borne by the member countries using the other International Bureau working language. All other costs involved in the supply of documents shall be borne by the Union. The ceiling of the costs to be borne by the Union for the production of documents in Chinese, German, Portuguese and Russian shall be fixed by a Congress resolution.
7. The costs to be borne by a language group shall be divided among the members of that group in proportion to their contributions to the expenses of the Union. These costs may be divided among the members of the language group according to another system, provided that the member countries concerned agree to it and inform the International Bureau of their decision through the intermediary of the spokesman of the group.
8. The International Bureau shall give effect to any change in the choice of language requested by a member country after a period which shall not exceed two years.
9. For the discussions at meetings of the Union’s bodies, the French, English, Spanish, Russian and Arabic languages shall be admissible, by means of a system of interpretation – with or without electronic equipment – the choice being left to the judgment of the organizers of the meeting after consultation with the Director General of the International Bureau and the member countries concerned.
10. Other languages shall likewise be admissible for the discussions and meetings mentioned in paragraph 9.
11. Delegations using other languages shall arrange for simultaneous interpretation into one of the languages mentioned in paragraph 9, either by the system indicated in the same paragraph, when the necessary technical modifications can be made, or by individual interpreters.
12. The costs of the interpretation services shall be shared among the member countries using the same language in proportion to their contributions to the expenses of the Union. However, the costs of installing and maintaining the technical equipment shall be borne by the Union.
13. Member countries and/or their designated operators may come to an understanding about the language to be used for official correspondence in their relations with one another. In the absence of such an understanding, the language to be used shall be French.