QUOTE(katyjay @ Jul 31 2006, 05:12 PM)

It's part of the mechanism of a grand piano that lets you play the same note repeatedly even though the key hasn't got all the way back up from being pressed the previous time.
Details
here.Cheers
Katyjay
Hi Maggiemay and Katyjay
Thanks for your replies.
Katyjay, yes! I browsed through that web page you included in your reply. Very informative. Shall study it. Thanks for the prompt reply!