This is an instance in which the original patent document by which we found the classification does not display the nature of the classification. This classification may involve peculiarities of design and technical principle which are not at all exclusive to aeronautics. This wiki has 1 patents in category "AT 30".
Patents in category AT 30
- Patent AT-1902-6911 (English title: Helmet facilitating respiration, Inventors: Ignaz Etrich, Filing date: 1901-06-13)
|Enclosing categories||Austrian patent classifications, Patent classification systems|