The point is that if the path says C:/, the file will at least be written to the path indicated in the result, and it gives people the correct syntax that they can append to. If the path does not exist, the file will be written to the current folder even though the result indicates it has been written to the specified path.
The suggestion I made for the same problem in Sample Printer was that the text for the control said “Unique, pre-existing output pathn(writes to current folder if empty/invalid)”.
Gale