Originally Posted by
Mike Jacoubowsky
For the TGV, no need to have anything punched by the yellow machines before boarding.
Um, yes you do have to punch normal TGV tickets, unless it's international. Punching the ticket serves a purpose: it shows that the ticket has been used, in case the conductor doesn't come around to punch it, and prevents one from trying to get a refund for a trip one actually took.
If you ever run out of time or forget to punch your ticket, find the conductor before s/he makes the rounds. If you come clean up front, they are generally lenient.