'Declaration Protected Friend Overrides NotOverridable ReadOnly Property UnderlyingItemsCount As Integer
protected internal override int UnderlyingItemsCount {get;}
Note: derived classes that append additional items (e.g. header records) can override this property to return the number of items not counting the appended ones.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, 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