When using the internal VBScript interpreter, it is possible to get hold of a reference to the local file system by using a statement like the following:
set fso = CreateObject("Scripting.FileSystemObject")
                This reference can then be used for operations towards the file system.
Example
This routine logs selection to a text file
Example:
sub LogFunction
	rem ** This routine logs selection to a text file **
	set fso = CreateObject("Scripting.FileSystemObject")
	set mypath = ActiveDocument.GetProperties
	directory = mypath.MyWorkingDirectory 
	On Error Resume Next
    rem ** See if file already exists. **
	set filFile = fso.GetFile(directory & "log.txt")
    rem ** If not, then create it. **
	if Err <> 0 then
		set filFile = fso.CreateTextFile(directory & "log.txt")
    end if
	set txsStream = filFile.OpenAsTextStream(8) 'For Appending
	set doc = ActiveDocument
	set mySelections = doc.fields("Field").GetSelectedValues
	for i = 0 to mySelections.Count - 1
		txsStream.WriteLine Now & " " & mySelections.Item(i).text
	next
	txsStream.WriteBlankLines 1
	txsStream.Close
end sub