Canadian first flight cover (FFC), from Kingston, Ontario, to Montreal, June 4 1929. The arms of Kingston appear on the cachet. Cachets on FFCs are usually not appropriate for thematic exhibits under FIP rules because they are considered private additions to the cover. However, the cachets of Canadian first flights of that period (1924-1934) had official authorization from the Canadian Post Office, and therefore can be included in a FIP competitive exhibition. This information is from the article "Oblitération Premier  Vol du Canada" by J.A. Desimpelaere, La Philatélie Thematique No. 148.