Thanks Prof. We did try with Wikipedia as well as net but couldn't understand the exact meaning / engineering visualisation. In fact the same is being discussed on one of our Technology-patents application in Japan.
It would be great if you could help us with something concrete on this..
Sorry, not sure of the context and also have never heard of a concatenated "KEY", so of no specific help.
The word only means things connected in series, so one or more pumps (or anything else) on the same shaft can be described as concatenated.
An interesting example that may help with the concept can be found here; http://www.patentstorm.us/patents/6911752/claims.html - sorry, link not available
(The first sentence of the claim has more than 150 words in it - no wonder we shy away from the patents office).
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If you can't explain it simply, you don't understand it well enough. (A.E.)