Result = MainXMLNode(#XML)Description
Returns the main XML node of the tree. A valid XML document must have one "main" or "document" node which contains all other nodes. Except this node, there can only be comments on the first level below the root node. The type of this node is #PB_Xml_Normal.
#XML The XML to use.
The main node, or zero if the tree has no main node (which happens if the tree is empty or the main node was deleted).