So I can't figure out what to put to get out of this Do Loop. It will
loop as long as the name inputed in the MsgBox is already a "bookmark"
(name). So I need it to stop looping, once a name is inputed that is
not already a "bookmark" (name).

Sub AddLoadCase()

Do
Dim mynum
mynum = InputBox("ENTER Load Case Name", "Load Case Namer")
If mynum = "" Then
Exit Sub
End If

Dim nm As name
On Error Resume Next
Set nm = ThisWorkbook.Names(mynum)
On Error GoTo 0
If Not nm Is Nothing Then
MsgBox "Name '" & mynum & "' already exists. Please Choose
Anther 'name'!"
End If
Loop Until ?????????????

Range("AD2:AK4").Copy
Range("B1000").End(xlUp).Offset(3, 0).PasteSpecial
Range("B1000").End(xlUp).Offset(0, 0).Select
Range("B1000").End(xlUp).Offset(0, 0).Value = mynum

End Sub