Postal Association Colour Scheme: at the suggestion of the Prussian post office in 1861 in the member countries of the German-Austrian Postal Association for
certain face values introduced uniform colours:
Universal Postal Union Colour Scheme: uniform colour scheme for 3 basic postal shipments proposed at the Universal Postal Congress in 1879 and contractually
agreed in 1906 in the respective 1st weight level in cross-border traffic: