expression.LowerHeadingLevel
expression Required. An expression that returns one of the objects in the Applies To list.
Remarks
Use the UpperHeadingLevel property to set the starting heading level. For example, to set the TOC field syntax {TOC \o "1-3"}, set the LowerHeadingLevel property to 3 and the UpperHeadingLevel property to 1.
Example
This example formats the first table of contents in the active document to show entries formatted with the Heading 2, Heading 3, and Heading 4 styles.
If ActiveDocument.TablesOfContents.Count >= 1 Then
With ActiveDocument.TablesOfContents(1)
.UseHeadingStyles = True
.UpperHeadingLevel = 2
.LowerHeadingLevel = 4
End With
End If