To copy and paste an excerpt of a sound item: (in Selection mode only)
•Select between blue 
and yellow 
the part to be copied.
•Click on "Copy" 
(or Ctrl + C).
•Place the reading head where you want to paste the clip.
•Click on "Paste" 
(or Ctrl + V).
NB: in block mode, if you copy and paste, the whole selected block is affected, without taking into account the blue and yellow lines.