Historical information

Exemptions from serving in the military were made during World War II to protect certain occupations. See this article from the Australian War Museum:
https://www.awm.gov.au/articles/encyclopedia/homefront/reserved_occupations#:~:text=In%20March%201942%20the%20list,for%20any%20change%20of%20employment.

Physical description

Certificate of Exemption from Service in the defence force. Granted to Herbert L. Vivian, as he was employed in a reserved occupation, as a fireman. Printed form, details typed in.