Maximum Cards. 
The Fundamentals of Philately defines maximum cards as “Pictorial postcards, pre-dating or reasonably contemporary with but not produced specifically for the purpose, duplicating the design of the stamp, with the stamp affixed to the pictorial side and cancelled with a postal marking relating as closely as possible to the picture. Some latitude is tolerated …”. The example shown of the Shrine is in full compliance and also has a first day cancel.
The Fundamentals of Philately by L.N. Williams, 1990, American Philatelic Society
APS Manual of Philatelic Judging and Exhibiting, 7th Edition, 2016.