AutoCAD Inventor :: How To Get Windows Username

I am trying to write a rule for restricting save rights to a .ipt or .iam file.  I am just starting out with ilogic and have very basic coding experience.What I would like is for the rule to read the windows login username and depending on the result (User A) displays a radio message box asking if if the file should be restricted.

If the file is to be restricted, then the rule should allow only User A to save the file.  Hopefully that makes sense.I have posted the code I have so far.  I don't know how to get the windows username so have substituted this with username for the moment.

If Username = "User A" ThenRestrictAccess = InputRadioBox("Should this file be restricted?", "Yes", "No", RestrictAccess, Title := "Restrict Access")End IfIf RestrictAccess = True And Username = "User A" ThenThisDoc.SaveElseThisDoc.Document.SaveAsEnd If