NCL has many types of audio-video materials, and starting in 2002, the digitization of these materials began. In addition to digitizing its own audio-visual materials, NCL also worked with TV and radio stations to digitize and preserve historically significant audio-visual materials. Some of the most noteworthy include daily news from Taiwan Television Enterprise (TTV) from 1962 to 2011, as well as recordings of important political and economic figures from the 1910s to the 1980s (such as Dr. Sun Yat-sen, Chiang Kai-shek and other presidents). There are also recordings of interviews of foreign dignitaries, speeches of prominent people in society, and radio dramas. As of December 2012, NCL’s Digital Audio Visual Archive System had already over 458,000 metadata records, and over 500,000 streaming files. The files are accessible either onsite in NCL or over the Internet, depending on the access rights granted. In order to make it easy to browse, the systems’ website lists 14 different topics, with 115 sub-categories; it also provides a search function. Beginning in 2013, a mobile version (http://mdava.ncl.edu.tw) and an app to play the audio-visual files with were made available.