The System.Web.UI.DataSourceCacheExpiry enumeration describes how data cached by a data source control expires in the ASP.NET cache. An ASP.NET data source control caches data in the ASP.NET cache based on a specified time-out period, which is set using the CacheDuration property. The System.Web.UI.DataSourceCacheExpiry describes how this time-out setting is used. If the expiration policy is set to DataSourceCacheExpiry.Absolute, the cached data is discarded when the amount of time specified passes since the data was first cached. If the expiration policy is set to DataSourceCacheExpiry.Sliding, the cached data is discarded only when the cache entry has not been used for the amount of time specified.