An expression of intent shall not be void for the expresser did not intend to be bound by it, except the fact was known to the other party.

A fictitious expression of intent made by the expresser in collusion with other party is void, but the voidance can not be a valid defense against any bona fide third party.
If the fictitious expression of intent was intended to conceal another juridical act, the provisions of the act with respect to such another juridical act shall apply.

If the expression was acting under a mistake as to the contents of his expression of intent, or had known the situation of affairs, he would not make the expression; he may revoke the expression; provided that the mistake or the ignorance of the affairs was not due to his own fault.
If a mistake in respect to the qualification of the other party or the nature of a thing is regarded as essential in trade, it shall be deemed a mistake as to the contents of the expression of intent.

If an expression of intent has been incorrectly transmitted by the person or institution employed for its transmission, it may be revoked under the same conditions as provided in the preceding article.

The right of revocation provided in the preceding two articles would be extinguished after one year from the date of expression.

If a expression of intent is revoked according to Article 88 or Article 89, the expresser is bound to compensate for any injury which the other party or any third party may have sustained by relying upon the validity of the expression, except the injured party knew, or might know, of the ground on which the expression was revocable.

An expression of intent which is procured by fraud or by duress may be revoked by the expresser. If the fraud was done by a third party, the expression may be revoked only under the circumstances that the other party knew, or might know the affairs.
The revocation of an expression of intent on the ground of fraud can not be a valid defense against the bona fide third party.

The right of revocation in the preceding article must be exercised within one year from the date when the fraud was discovered or when the duress ceased. But it can not be exercised after ten years since the expression of intent.

An expression of intent inter presents becomes effective at the moment when the person to whom it is made understands it well.

An expression of intent inter absents becomes effective at the moment when the notification of the expression reaches such other party, except when the withdrawal of the notification previously or simultaneously reaches such other party.
The fact that after the notification of the expression the expresser dies, or becomes no capacity to make juridical acts, or is limited in capacity to make juridical acts, shall not null the expression of intent.

If an expression of intent is made to a person with no capacity or limited in capacity to make juridical acts, it becomes effective when the notification of the expression reaches the guardian of the person.

If an expresser, not due to his fault, is ignorant of name and residence of the other party, the notification of the expression may be effected by the service by publication according to the Civil Procedure Code.

In the interpretation of an expression of intent, the real intention of the parties must be sought rather than the literal meaning of the words.