Gets or sets the last save date and time or null if the "Last save time" property is undefined. All retunred times will be
DateTimeKind.Utc, and non-Utc DateTime's will be converted to DateTimeKind.Utc at the time they are set. Setting this property to null has the same effect as calling
IDocumentProperty.Delete on the associated document property.
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2