Private Sub Document_New()
  
  Dim af As String
  
  af = ActiveDocument.Bookmarks("af_").Range.Text
  ' MsgBox af
  If af = "." Then Exit Sub

  SubstantiveIssue
  SetAsAlreadyFilled
  
  RemoveKeyBinding
  AddKeyBinding
  
End Sub

Sub SubstantiveIssue()

   ' do somethings
   
End Sub

Sub SetAsAlreadyFilled()

   ' do somethings

End Sub

Sub AddKeyBinding()
    With Application
         ' \\ Do customization in THIS document
        .CustomizationContext = ActiveDocument
         
         ' \\ Add keybinding to this document Shorcut: Alt+Z
        .KeyBindings.Add KeyCode:=BuildKeyCode(Arg1:=wdKeyAlt, Arg2:=wdKeyZ), KeyCategory:=wdKeyCategoryCommand, Command:="SubstantiveIssue"
        
      ' MsgBox Application.CustomizationContext
      ' MsgBox "AddKeyBinding = " & .FindKey(BuildKeyCode(Arg1:=wdKeyAlt, Arg2:=wdKeyZ)).Command
    End With
    
  ' MsgBox "add Binding = " & Application.FindKey(BuildKeyCode(Arg1:=wdKeyAlt, Arg2:=wdKeyZ)).Command
End Sub

Sub RemoveKeyBinding()
  With Application
    .CustomizationContext = ActiveDocument
    .FindKey(BuildKeyCode(Arg1:=wdKeyAlt, Arg2:=wdKeyZ)).Clear
  End With
End Sub

Private Sub Document_Open()
 ' MsgBox "open Binding = " & Application.FindKey(BuildKeyCode(Arg1:=wdKeyAlt, Arg2:=wdKeyZ)).Command
 RemoveKeyBinding
 AddKeyBinding
End Sub

Private Sub Document_Close()
 RemoveKeyBinding
End Sub

.KeyBindings.Add KeyCode:=BuildKeyCode(Arg1:=wdKeyAlt, Arg2:=wdKeyZ), KeyCategory:=wdKeyCategoryCommand, Command:="SubstantiveIssue"