1. A European patent application may be filed:
a) with the European Patent Office, or
b) if the law of a Contracting State so permits, and subject to Article 76, paragraph 1, with the central industrial property office or other competent authority of that State. Any application filed in this way shall have the same effect as if it had been filed on the same date with the European Patent Office.
2. Paragraph 1 shall not preclude the application of legislative or regulatory provisions which, in any Contracting State:
a) govern inventions which, owing to the nature of their subject-matter, may not be communicated abroad without the prior authorisation of the competent authorities of that State, or
b) prescribe that any application is to be filed initially with a national authority or make direct filing with another authority subject to prior authorisation.