True if the specified style is a built-in style that has been modified or applied in the document or a new style that has been created in the document. Read-only Boolean.
Assembly: Microsoft.Office.Interop.Word (in Microsoft.Office.Interop.Word.dll)
This property doesn't necessarily indicate whether the style is currently applied to any text in the document. For instance, if text that's been formatted with a style is deleted, the InUse property of the style remains True. For built-in styles that have never been used in the document, this property returns False.