NextSubdocument Method
From Microsoft Word Visual Basic
Moves the range or selection to the next subdocument. If there isn't another subdocument, an error occurs.
expression.NextSubdocument
expression Required. An expression that returns a Range or Selection object.
Example
This example switches the active document to master document view and selects the first subdocument.
If ActiveDocument.Subdocuments.Count >= 1 Then
ActiveDocument.ActiveWindow.View.Type = wdMasterView
Selection.HomeKey unit:=wdStory, Extend:=wdMove
Selection.NextSubdocument
End If