Libraries acquiring sound and audio-visual material face strong legal constraints that go beyond the duties involved in all public procurement. In the case of CDs, lending is theoretically subject to authorisation, since the law only provides for the CD to be played on site. Lending to library users is tacitly tolerated. The rise of digital forms of music has had a number of consequences: digital recordings can still be played on site, but it seems that they cannot be lent without some form of contract. Further, while a 2006 law allows libraries to digitise their collections for safekeeping, the limits of what can be done with such recordings have yet to be set. In the case of audio-visual material, libraries can only purchase and lend physical (DVDs) and virtual (VOD) formats under certain highly restrictive contractual conditions.