Music.Backups

		type Backup
	Public representation.

		type Backup_Access
	Pointer to representation data.

		function Create
	Constructor for instances.
	Param  Type  Description in Duration  Positive  The initial duration. return  Backup_Access  The newly created backup.

		function Get_Duration
	Accessor to read the duration of a backup.
	Param  Type  Description access This  Backup  The backup to read from. return  Positive  The duration of that backup.