The term "Kundschaft" (engl. clientele) was used to describe the certificate issued to a journeyman upon completion of his work at a particular location. As part of their training, journeymen had to complete a period of wandering prescribed by the guilds, which took them to various cities. In the "Kundschaft," their good conduct and proper completion of service was confirmed by the local guild. The wording of the certificates was always the same and had been laid down in the Reichshandwerksordnung (handicrafts regulation) of 1731.
"Kundschaft" for a journeyman carpenter, copperplate engraving, 1818, unknown artist, photographer: Alfred Löhr; source: Alfred Löhr (ed.): Das alte Handwerk in Bremen, Arbeitsmappe Schule und Museum, Bremen 1987, Wikimedia Commons https://commons.wikimedia.org/wiki/File:Kundschaft.jpg, Attribution-ShareAlike 4.0 International (CC BY-SA 4.0), https://creativecommons.org/licenses/by-sa/4.0/deed.en.