Usage of bookmarks (VB)

'This sample demonstrates as to apply bookmarks,
'using IB Provider and Active Data Objects, for data access to an Interbase

Sub Sample13()

    'connection
    Dim con As New ADODB.Connection
    'recordset
    Dim rs As New ADODB.Recordset
    'bookmark
    Dim dblBookmark As Double
    'other declares
    Dim strMessage As String

        'open connection
        con.Open "file name=" & ThisWorkBook.Path & "\Db.ibp"
        con.BeginTrans 'start transaction

        rs.ActiveConnection = con 'set the active connection
        'Creation of recordset with the bidirectional access
        rs.Properties("Fetch Backwards") = True
        rs.Properties("Scroll Backwards") = True
        'use bookmarks
        rs.Properties("Use Bookmarks") = True
        'open recordset
        rs.Open "select * from employee"

        Do While True
           ' Show information about current employer and get
           ' user input.
            strMessage = "Employer: " & rs!first_name & " " & _
                                        rs!last_name & " " & _
                                        rs!last_name & " " & _
                    "Enter command:" & vbCr & _
                    "[1 - next; 2 - previous;" & vbCr & _
                    "3 - set bookmark; 4 - go to bookmark; else exit]"

                Select Case Val(InputBox(strMessage, "Enter the command number (Fetched " & _
                                                     rs.RecordCount & " records)"))
                    ' Move forward or backward, trapping for BOF
                    ' or EOF.
                    Case 1
                        rs.MoveNext
                        If rs.EOF Then rs.MoveLast
                    Case 2
                        rs.MovePrevious
                        If rs.BOF Then rs.MoveFirst
                    ' Store the bookmark of the current record.
                    Case 3
                        varBookmark = rs.Bookmark

                    ' Go to the record indicated by the stored
                    ' bookmark.
                    Case 4
                        If IsEmpty(varBookmark) Then
                            MsgBox "No Bookmark set!"
                        Else
                            rs.Bookmark = varBookmark
                        End If

                    Case Else 'if user enter not in (1,4) then exit
                        Exit Do
                End Select

        Loop

        'close all objects
        rs.Close
        con.CommitTrans
        con.Close

End Sub