SpreadsheetGear & VB.Net -> Workbook.Names

Hello,

I am new to SpreadsheeetGear which is a tool that allows excel interactions with VB.Net.
On looking at the sample V.Net source  code at http://www.spreadsheetgear.com/support/samples/srcview.aspx?file=amortizationVB.aspx and the associated Excel spreadsheet it interacts with I note in the source code it has the following:

        ' Open the workbook.
        Dim filename As String = Server.MapPath("files/amortization.xls")
        Dim workbook As SpreadsheetGear.IWorkbook = SpreadsheetGear.Factory.GetWorkbook(filename)
   
        ' Get IRange for cells from defined names.
        Dim pv As SpreadsheetGear.IRange = workbook.Names("PV").RefersToRange
        Dim rate As SpreadsheetGear.IRange = workbook.Names("Rate").RefersToRange
        Dim nper As SpreadsheetGear.IRange = workbook.Names("NPer").RefersToRange

Within the Excel sheet the following is displayed (where "Loan Amount (PV)" and "Annual Interest Rate (Rate)" etc are in column A and "$15,000.00" is in column B etc........

Loan Amount (PV)      $15,000.00
Annual Interest Rate (Rate)      7.25%
Total # of Months (NPer)      24

While "PV", "Rate", and "NPier" are written in column A as "Loan Amount (PV)" etc... in the excel worksheet there is no other reference to such abbreviations.

My question in relation to this is: When it states "Dim pv As SpreadsheetGear.IRange = workbook.Names("PV").RefersToRange" in the VB.Net code, is it actually looking up the excel sheet for the equivalent column/value PV? I presume" PV" is hardly just defined in the worksheet by using "Loan Amount (PV)"?

If anyone can explain how this works & what the IRange values are doing then I'd appreciate all help.

Thanking you in advance