It is improper to convey information to a partner by means of a call or play based on a special partnership agreement, whether explicit or implicit, unless such information is fully and freely available to the opponents (see Law 40).
It is not improper for a player to violate an announced partnership agreement, so long as his/her partner is unaware of the violation (but habitual violations within a partnership may create implicit agreements, which must be disclosed). No player has the obligation to disclose to the opponents that s/he has violated an announced agreement.
If the opponents are subsequently disadvantaged i.e. by drawing a false inference from such violation, they are not entitled to redress.
When explaining the significance of partner’s call or play in reply to an opponent’s inquiry (see Law 40), a player should disclose all special information conveyed through the partnership agreement or experience; but she/he need not disclose inference drawn from general bridge knowledge and experience.
It is improper for a player whose partner has given a mistaken explanation to correct the error immediately or to indicate in any manner that a mistake has been made. She/he must not take any advantage of the unauthorised information so obtained. She/he is under no obligation at any later time to inform the opponents that the explanation was erroneous. If a player subsequently realises that his/her own explanation was erroneous or incomplete, she/he should immediately call the Director (who will apply Law 21 or Law 40(b)).