title: how to get the earliest date Excel support programmatically
body: <p>Excel AddIn, C#, UDF, 
  MyUDF calls a web service to retrieve certain date. Sometimes the date returned is not in range of Jan-1-1900 to Dec-31-9999 (Excel Date Range). E.g. in one case returned date is Jan-2-0002 (valid in C# but not valid in Excel), then Excel crashes.  I do not hard code "Jan-1-1900", so wonder if there is a way that I can get it programmatically. thanks </p>