The history of the Österreichische Nationalbibliothek can be traced back to the literary holdings of Emperor Maximilian I (1493-1519), some of whose volumes passed into the imperial Hofbibliothek in Vienna in the sixteenth century. From uncertain beginnings the library progressed consistently, gathering rarities and reputation. Known until 1918 as the Kaiserliche und königliche Hofbibliothek and since then as the Österreichische Nationalbibliothek, its collection of some 30,000 manuscripts is one of the most important in the world. Approximately 14,000 codices in various languages (including Latin, German, Greek, and other European languages; also Arabic, Ottoman Turkish, Persian, Ge'ez, etc.) were filmed for HMML. In addition, tens of thousands of papyri fragments from the Papyrussammlung were also filmed. A portion of this collection was later digitized by the Zaydī Manuscript Tradition project (ZMT). This contains manuscripts of Zaydī origin, mostly from Yemen, including numerous works on Zaydī law and history along with Muʻtazilī theology.