SMPTE RP 190-1996 (Stabilized 2012)

This practice specifies the desirable storage conditions for audio magnetic recordings of continuing value, as they may remain in library or vault storage between periods of intermittent reproduction or duplication. Two categories of storage time are defined. The categories are in agreement with those defined by ANSI/NAPM IT9.11-1993.
Medium-term storage conditions: Storage conditions suitable for the preservation of recorded information for a minimum of ten years.
Extended-term storage conditions: Storage conditions suitable for the preservation of recorded information having permanent value.