A bilateral modification is also known as what type of agreement?

A bilateral modification is also known as a supplemental agreement because it involves changes to the terms of an existing contract that require the mutual consent of both parties. In such an agreement, both parties must agree to the modified terms, which is indicative of a bilateral nature. This type of modification is often used to revise contract terms while maintaining the overall framework of the original agreement.

The term "supplemental" specifically emphasizes that this modification adds to or alters the existing contract without completely replacing it. This aligns with the concept in contracting practices where both parties collaborate to confirm and revise conditions, ensuring that the interests of each side are represented in the new terms.

Other terms, such as unilateral and collective agreements, do not apply in this context because they refer to different types of agreements that either involve one party making a change without the other's consent or involve broader negotiations typically used in labor relations or large group contracts. Additionally, "Modification Agreement" is a general term that could apply to both bilateral and unilateral agreements, but it doesn't specifically denote the cooperative aspect inherent in a supplemental agreement involving mutual consent.