Sub EcrireDansPlage()
Dim entete$, valeur, LO As ListObject, P As Range, col As Variant
entete = "Ref_op"
valeur = 9999 'à adapter
ActiveCell.Activate 'au cas où la sélection n'est pas un Range
For Each LO In ActiveSheet.ListObjects
With LO.Range
Set P = Intersect(Selection, .Cells)
If Not P Is Nothing Then
col = Application.Match(entete, .Rows(1), 0)
If IsNumeric(col) Then
Intersect(P.EntireRow, .Columns(col)) = valeur
.Cells(1, col) = entete
End If
End If
End With
Next
End Sub