Cheers for input re bookings etc. Here's the official guidlines from Uefa:
Article 21
Yellow and red cards:
21.01 As a rule, a player who is sent off the field of play is suspended for the next match in the competition.The Control and Disciplinary Body is entitled to augment this sanction.
21.02 A player is automatically suspended for the next competition match after two cautions in two different matches as well as after the fourth and any subsequent caution.
21.03 Cautions and pending yellow-card suspensions expire on completion of the qualifying competition. They are not carried forward to the final tournament Final tournament
21.04 Single cautions from matches in the final tournament expire on completion of the quarter-finals, and are not carried forward to the semi-finals.
21.05 Cautions and pending yellow-card suspensions from the final tournament expire at the end of the competition.