-none rule is very useful in the case where a file that should not be seen within a view and the other methods of hiding the file are not a viable choice.
In a dynamic view:
Generates a File not found or No such file or directory error when an operating system program references the element by name.
No error occurs when an operating system command or utility program lists the element's containing directory, though the element is not included in such a listing. This also applies to situations such as expansion of wildcard characters and file name completion.
The cleartool ls command always lists the element, annotating it with no version selected.
In a snapshot or Web view:
For elements that are not loaded into the view, generates an error and does not load the element.
For elements that are loaded into the view, generates an error during update but does not unload the element
element * CHECKEDOUT
element file.txt -none
element * /main/LATEST