In the case of an agreement for the assignment of the exclusive right to inventions, utility models, industrial models, trademarks, the transfer of rights of the contract is subject to state registration. The legal consequence of non-compliance with the written form of the contract and the requirements of the public registration of the transfer of rights is its nullity of the contract. If the exclusive right has not been transferred to the assignee, the right holder may unilaterally waive the contract and pay damages if he does not fulfil his obligation to pay for the acquisition of the exclusive right within the period set by the contract and if he can unilaterally waive the contract and claim damages for breach of contract. As a general rule, certain types of loans are always excluded from a sale clause that is due. These include VA loans, USDA loans, and FHA loans. .