Single source PATHCOPY

If the source references a single value, then that value is copied to all elements in the destination tree. Examples of a single value are a complete path, temporary variable, or a constant. This updates the values of all #text nodes or attributes that are currently present in the destination sub-tree referenced by the destination path.

By copying @null, a sub-tree can be removed from the destination XML message. If the destination path specifies a repetition, then only that specific repetition is modified.

Note: A source path referencing a destination value cannot be used. That is, "~" at the beginning of the path. This is a limitation that XML shares with other message formats.