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The user selects / deselects files by pressing the [Space Bar]. The 
status of the file next to the cursor will be toggled between selected and 
deselected.
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The user can SELECT ALL the files via 'A' (all), and DESELECT ALL files via 'Z' 
(zap). 
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Also the user can SELECT SPECIFIC files based on a (partial) 
file specification via '+', and DESELECT in a similar way via '-', using
wildcards.
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At least one file must be selected for the Copy, Delete, Move, Rename and List 
options.