(3) In the event of the aforesaid 6th Edition of the International Classification of Goods and Services, 1992, being amended by the World Intellectual Property Organisation at any future stage, the Registrar shall publish such amendments in the Patent Journal and shall, to the extent that such amendments necessitate an amendment of Schedule 3 to these regulations, so amend Schedule 3 and publish such amendment. (4) If any doubt arises as to the class in which any particular description of goods or services belongs, the matter shall be determined by the Registrar. 5. Documents [Section 69(2)] Subject to any directions that may be given by the Registrar, all documents required by the Act or by these regulations to be filed with the Registrar shall be typewritten, lithographed or printed in one of the official languages of the Republic in legible roman characters with black ink upon strong paper, on one side of the paper only, of A4 standard size and shall have on the left hand side a margin of at least 35 mm. Provided that the requirements of this regulation are met if documents have been lodged in accordance with the operational requirements and proof of payment of the prescribed fee (if any), has been provided. 6. Service of documents [Section 66] (1) Any document to be filed with the Registrar may be sent through the post or in such electronic form and by such electronic means as authorized by the Registrar for electronic services. Any such document so sent shall not be deemed to have been duly sent until it is received by the Registrar. (2) Any document to be served on any person other than the Registrar may be sent by registered post. Any document so sent shall be deemed to have been delivered in the ordinary course of post, and in proving such service or sending it shall be sufficient to prove that such document was properly addressed and put into the post and registered. (3) Any affidavit to be filed with the Registrar or served on any other person in terms of regulations 19 and 52(2) may be sent by facsimile transmission or in such electronic form and by such electronic means as authorized by the Registrar for electronic services. Such transmitted copy or original electronic document, as the case may be, shall be received 6