It's fair to say that it still happens nowadays, some people don't differentiate between the abbreviations c.a k. and c.k., as if they don't know what this difference means. Well, let's recall that as a result of the so-called settlement of 1867, the Austrian Empire is divided into two parts
with different constitutions. To Pre-Lithuania (Cislajtania), i.e. the kingdom and the country represented in the Reich Council in Vienna, where the feudal authorities and the army administered by the own Ministry of Land Defense (Landwehr) are k. k. (Kaiserlich-kániglich), in Czech
c. k. (imperial-royal). Then to Zalitavsko (Translajtania), i.e. the land of the Hungarian crown, where everything is m. k. (magyar király), in German k. u. (königlich ungarisch), i.e. royal Hungarian. An earth barrier is called a honvédség. On the basis of a handwritten imperial letter dated November 14, 1868, it is ordered to continue to use the name Austro-Hungarian Empire, Austro-Hungarian Empire. The monarch is, according to the so-called minor title, Emperor of Austria, King of Bohemia, etc., and Apostolic King of Hungary, while the completely brief title His c. and k. Apostolic Majesty is not a mistake either. The ruler also has a large title (see VIRIBUS UNITIS), correspondingly extensive, at the end of which is nevertheless attached the in no way specified etc., etc., or usw, usw, Czech, etc., etc. Everything that is common to both parts of the monarchy, i.e. affairs of the Imperial House and Foreign Affairs, Imperial Finance and the Army in the Department of the Imperial Ministry of War, is k. u. k. (kaiserlich und königlich), in Czech c. and k. (imperial and royal). However, the joint army was endowed with the inserted letter "a" only on October 17, 1889, when Francis Joseph I issued the Supreme Order, published in the Bulletin c. and k. of the Reich Ministry of War as a circular of the presidential department file no. 55871: "According to the custom observed since my ancestors, according to which the name of the military power of the monarchy is always administered according to the title of Supreme Landlord and Commander of the Army, I have deemed it good to order by the order just issued that my army and my war fleet from now on , instead of the previous name, it called imperial and royal."
(According to the book Encyclopedia for lovers of Švejk)