If anything in cell.. then put period in cell beside

Place this macro in the SHEET MODULE so it is active all the time. It will watch for activity in column D. If any cell in column D is changed, it place a period in column E. If the change CLEARS a cell in column D, the column E period would be removed, too.

Option Explicit

Private Sub Worksheet_Change(ByVal Target As Range)
Dim cell As Range

On Error Resume Next
For Each cell In Intersect(Target, Range("D:D"))
    Application.EnableEvents = False
    If cell <> "" Then
        cell.Offset(, 1) = "."
    Else
        cell.Offset(, 1) = ""
    End If
    Application.EnableEvents = True
Next cell

End Sub