It's not exactly clear what determines the decision to process by tag or title. Perhaps something along the lines of:
Code:
Private Sub Document_ContentControlOnExit(ByVal oCC As ContentControl, Cancel As Boolean)
Dim i As Long
With ActiveDocument
Select Case oCC.Tag
Case "a"
For i = 1 To .SelectContentControlsByTag(oCC.Title).Count
.SelectContentControlsByTag(oCC.Title)(i).Range.Text = ""
Next
End Select
End With
End Sub
or:
Code:
Private Sub Document_ContentControlOnExit(ByVal oCC As ContentControl, Cancel As Boolean)
Dim i As Long
With ActiveDocument
For i = 1 To .SelectContentControlsByTag(oCC.Tag).Count
.SelectContentControlsByTag(oCC.Tag)(i).Range.Text = ""
Next
End With
End Sub