if you can edit Xml, you can fix it by specifying a namespace for it
<use xlink:href="#lend13" transform="scale(-8.5,-8.5) xmlns:xlink="http://myurl.com/" />
otherwise, you can predefine the namespace when using XmlDocument
XmlDocument.DocumentElement.SetAttribute("xmlns:xlink", "http://myurl.com/");
and in linq for XML you can define an attribute using XNamesace
XNamespace ns = "http://myurl.com/";
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