In the course of preliminary examination attention is mainly paid to the requirements relating to the formal requirements, sufficient data concerning the patent applicant, the letter of authorisation, priority documents, payment of the fees in due time etc. If any deficiencies or ambiguities occur, the applicant shall be notified thereof and explanations will be asked for. Special attention is drawn to the compliance of the application documents with requirements relating to the formal requirements (sheet size, margins, legibility of the text, and compliance of the drawings with the technical drawing requirements). Non-compliance with the formal requirements is an obstacle and technically hinders the publication of the patent application. Therefore deficiencies are asked to be eliminated. If explanations are not provided or the deficiencies are not eliminated by the due date, the Patent Office will reject the patent application.