This book is aimed at all railway enthusiasts: fans of old and new locomotives, model railroaders, technical historians, and collectors of signs will receive a complete overview of the inventory of German vehicle types in one book, which even specialists find difficult to grasp, and which is not represented in this form by the existing literature. After the legendary first "Maey/Born" in the 1920s, only the long out-of-print "Directory of German Locomotives 1923-1963" was published. This comprehensive directory begins with the renumbering of state railway locomotives in 1925 and for the first time includes the systematics of computer numbers from DB and DR up to 1970. The well-known railway historian Andreas Knipping provides a comprehensive assessment of the historical German numbering system for the first time.