True if the style is automatically redefined based on the selection. False if Word prompts for confirmation before redefining the style based on the selection. A style can be redefined when it's applied to a selection that has the same style but different manual formatting. Read/write Boolean.
Example
This example creates a style named "Style1" that can be redefined without the need for confirmation.
Dim docNew as Document
Dim styleNew as Style
Set docNew = Documents.Add
Set styleNew = docNew.Styles.Add("Style1")
With styleNew
.BaseStyle = docNew.Styles(wdStyleNormal)
.ParagraphFormat.LineSpacingRule = wdLineSpaceDouble
.AutomaticallyUpdate = True
End With