Which of the following is not a valid property of blanket contracts?

The property that is not valid for blanket contracts is "Process Claim." Blanket contracts typically serve as overarching agreements that provide a framework for procuring a specified quantity of goods or services over a set period. They simplify the purchasing process by allowing multiple orders against a single contract without renegotiating terms.

In terms of valid properties, "Payment Terms," "Expiration Date," and "Contract Amount" are all essential components that outline the financial arrangements, the validity period, and the maximum spend or quantity under the contract.

"Payment Terms" detail how and when the supplier will be compensated for the goods or services delivered. An "Expiration Date" indicates how long the contract remains effective, and the "Contract Amount" specifies limits on spending within the contract. None of these properties directly relate to operational procedures regarding claims processes, which is why "Process Claim" is deemed invalid in the context of blanket contracts.