参数设定函数看不懂，望指教

ygsh16

在一个串口程序中，参数设定函数看不懂，望指教
1）cboParity.AddItem与后面的Select Case对应吗？前面
cboParity.AddItem "Even"
cboParity.AddItem "Odd"
cboParity.AddItem "None"
cboParity.AddItem "Mark"
cboParity.AddItem "Space"
我这样认为对不对：Even的ListIndex是0，Odd是1，以此类推
如果是这样，后面Select Case是不是错了？
2）还有Echo始终找不到定义，但程序能运行，不知为啥？
Sub LoadPropertySettings()
Dim i As Integer, Settings As String, Offset As Integer
' Load Port Settings
For i = 1 To 16
    cboPort.AddItem "Com" & Trim$(Str$(i))
Next i

' Load Speed Settings
cboSpeed.AddItem "110"
cboSpeed.AddItem "300"
cboSpeed.AddItem "600"
cboSpeed.AddItem "1200"
cboSpeed.AddItem "2400"
cboSpeed.AddItem "4800"
cboSpeed.AddItem "9600"
cboSpeed.AddItem "14400"
cboSpeed.AddItem "19200"
cboSpeed.AddItem "28800"
cboSpeed.AddItem "38400"
cboSpeed.AddItem "56000"
cboSpeed.AddItem "57600"
cboSpeed.AddItem "115200"
cboSpeed.AddItem "128000"
cboSpeed.AddItem "256000"

' Load Data Bit Settings
cboDataBits.AddItem "4"
cboDataBits.AddItem "5"
cboDataBits.AddItem "6"
cboDataBits.AddItem "7"
cboDataBits.AddItem "8"

' Load Parity Settings
cboParity.AddItem "Even"
cboParity.AddItem "Odd"
cboParity.AddItem "None"
cboParity.AddItem "Mark"
cboParity.AddItem "Space"

' Load Stop Bit Settings
cboStopBits.AddItem "1"
cboStopBits.AddItem "1.5"
cboStopBits.AddItem "2"

' Set Default Settings

Settings = Form1.MSComm1.Settings

' In all cases the right most part of Settings will be 1 character
' except when there are 1.5 stop bits.
If InStr(Settings, ".") > 0 Then
    Offset = 2
Else
    Offset = 0
End If

cboSpeed.Text = Left$(Settings, Len(Settings) - 6 - Offset)
Select Case Mid$(Settings, Len(Settings) - 4 - Offset, 1)
Case "e"
    cboParity.ListIndex = 0
Case "m"
    cboParity.ListIndex = 1
Case "n"
    cboParity.ListIndex = 2
Case "o"
    cboParity.ListIndex = 3
Case "s"
    cboParity.ListIndex = 4
End Select

cboDataBits.Text = Mid$(Settings, Len(Settings) - 2 - Offset, 1)
cboStopBits.Text = Right$(Settings, 1 + Offset)
cboPort.ListIndex = Form1.MSComm1.CommPort - 1
optFlow(Form1.MSComm1.Handshaking).Value = True
If Echo Then
    optEcho(1).Value = True
Else
    optEcho(0).Value = True
End If
End Sub

ygsh16

附件是串口程序。
望热心人指教，初学者，问题有可能肤浅，见谅