Final answer:
A fixed-price or lump-sum contract is a standard agreement between an owner and a contractor with payment as a stipulated sum, which includes provisions for change orders, installments, and interest on late payments.
Step-by-step explanation:
The standard form of agreement between the owner and contractor where the basis of payment is a stipulated sum is commonly referred to as a fixed-price or lump-sum contract. This type of contract specifies that the contractor agrees to provide specified services for a specific price. In the context of such contracts, change orders are an important feature, allowing for the modification of the scope of work agreed upon by both parties.
The owner typically pays the contractor the agreed-upon sum in installments, as detailed in invoicing and payment clauses within the contract, which might also include terms related to interest on late payments.