Attributes are maintained in the XML tree in the order that they were added to the element. When a collection of attributes is returned by Attributes, they are returned in the order that they were added, and are not sorted. When you request the previous attribute through this property, this property returns the attribute that was added before this attribute.
If this attribute does not have a parent, or if this attribute is the first attribute, then this property returns nullptr.
The XElement class stores its attributes as a singly-linked list of XAttribute objects. This means that the PreviousAttribute property must traverse the list of attributes that belong to the element. Therefore, using this property might affect your performance.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)