dim,

No, you can't get off at any station. If you buy a ticket from Madrid to Barcelona it will say "Madrid - Barcelona / train # date, time". If you got off at Zaragoza, you couldn't get on again later since your ticket is only valid for an specific train on a given date and time.

However, you could buy a round trip ticket Madrid - Zaragoza and another one Zaragoza - Barcelona.

As for the discounts, you get 20% discount with the Carnet Joven ( Euro < 26 ). You can also get discount using the Explorer rail and the Eurorail passes.

Regards,

Antonio

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Hostal Chelo at http://www.chelo.com