For the cheap RES-say up to 10€-normally not. In some countries/cases you MAY be able to excahnge them for a same-same IN that country at a counter.
For the more expensive ones, f.e. also €*-you have to contact where you booked it-and these will also set the rules.
It should be evident to always check first any conditions etc that are usually sent out together with the mail that allocates the seats etc. and not let other tell you to do that first!
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