Recital 27 Member States should, therefore, be required to provide for an exception to permit cultural heritage institutions to reproduce works and other subject matter permanently in their collections for preservation purposes, for example to address technological obsolescence or the degradation of original supports or to insure such works and other subject matter. Such an exception should allow the making of copies by the appropriate preservation tool, means or technology, in any format or medium, in the required number, at any point in the life of a work or other subject matter and to the extent required for preservation purposes. Acts of reproduction undertaken by cultural heritage institutions for purposes other than the preservation of works and other subject matter in their permanent collections should remain subject to the authorisation of rightholders, unless permitted by other exceptions or limitations provided for in Union law.