What do the yellow, green and red cards mean in shotgun shooting?

• Spoken as well as shown: a card is accompanied by the word "Warning", "Deduction" or "Disqualification". A warning does not have to come before a deduction or a disqualification.
• Technical violations: a foot fault; exceeding the time limit to call; following or pointing the gun at a slow or fast target without shooting.
• First technical violation: yellow card, noted on the scorecard.
• Second or later of the same kind: one point deducted by the referee, at any stage of the competition except the final.
• Open violations: dress code, unnecessary interruption, illegal coaching, unsportsmanlike conduct, shooting out of turn. A warning first, so the fault can be corrected.
• Deductions by the jury: one point for impeding another athlete in an unsportsmanlike manner, for knowingly giving false information or for interfering with range equipment after a first violation. Two points for reporting late to a final.
• Leaving the range: an athlete who leaves without finishing the round and without permission loses all the remaining targets of the round.
• Disqualification: for serious safety breaches, handling a loaded shotgun after "STOP", repeating an offence already warned or penalised, deliberate abuse of an official, deliberately concealed violations and violations involving shotguns or ammunition.
• Who decides: a referee gives warnings and the automatic deductions. Disqualification needs a majority of the jury.

Most breaches are small and unintended, so the first answer is a warning that lets the athlete put it right. A point is a heavy price in a sport where finals are reached on a single target, which is enough to stop repeats. Disqualification is kept for danger and dishonesty.