Bilateral modifications can be used to definitize what type of contracts?

Bilateral modifications are a crucial aspect of contract management, particularly when it comes to certain types of contracts that require agreement from both parties to change any contract terms. In the context of this question, letter contracts, also known as undefinitized contract actions (UCAs), are a specific type of contract used primarily in government contracting.

A letter contract is a preliminary agreement that allows work to commence before final terms are negotiated and agreed upon. Because these contracts are not fully executed initially, they are subject to further negotiation and modification. Once the definitive terms are agreed upon — for example, after the work has begun and the necessary details have been established — a bilateral modification can be used to finalize the contract terms. This process ensures that both parties have reached an agreement and legally formalizes the modifications.

The other types of contracts listed do not typically involve this specific process of bilateral modification in the same context. Exclusive contracts, private contracts, and public contracts can have their own terms of negotiation and adjustment, but they do not specifically rely on the concept of undefinitized actions that necessitate the use of a letter contract format for definitization purposes.