Inserts the specified node immediately before the specified reference node.
Assembly: System.Xml (in System.Xml.dll)
The current node is of a type that does not allow child nodes of the type of the newChild node.
The newChild is an ancestor of this node.
The newChild was created from a different document than the one that created this node.
The refChild is not a child of this node.
This node is read-only.
If refChild is null, insert newChild at the end of the list of child nodes. If newChild is an XmlDocumentFragment object, its child nodes are inserted, in the same order, before refChild. If the newChild is already in the tree, it is first removed.
If the node being inserted was created from another document, you can use XmlDocument.ImportNode to import the node to the current document. The imported node can then be inserted into the current document.