>Does anybody know what function to use to retrieve the User Name from the machine that the user is logged in?

There are several ways to do this; the easy one is to use the Windows Scripting Host's Wscript.Network Automation object if Windows Scripting Host is installed on your system:

oWSHNet = CREATEOBJ('Wscript.Network')
? oWshNet.UserName

If the Windows Scripting Host is not installed, you can use any of several Win32API calls; the simplest is WNetGetUser()

DECLARE INTEGER WNetGetUser IN WIN32API ;
   STRING lpDeviceName, ;
   STRING lpUserNameBuffer, ;
   INTEGER @BufferLength
cBuffer = REPL(CHR(0),256)
nBufSize = 256
IF WNetGetUser(0, @cBuffer, @nBufSize) = 0
   *  Got it
   ? LEFT(cBuffer,nBufSize - 1)
ELSE
   *  Something went wrong
ENDIF

This will retrieve the login name for the local machine. If you wanted to see how the user was logged in to access a particular device, such as a mapped network drive Z:, you would use 'Z:'+CHR(0) in place of the first argument, ie

IF WNetGetUser('Z:'+CHR(0), @cBuffer, @nBufSize)