The typical purpose of a change order in construction contracts is to:

The typical purpose of a change order in construction contracts encompasses a variety of adjustments, which is why "all of the above" is the most comprehensive answer. A change order can serve to increase the contract sum when additional work or materials are required beyond what was initially agreed upon. This might occur due to unforeseen circumstances, changes in scope, or client requests.

Conversely, a change order can also decrease the contract sum if there are reductions in scope or the removal of certain work elements from the contract. Adjustments may arise from negotiations or design modifications that lead to cost savings.

Additionally, change orders frequently modify the contract's schedule or time of completion. Delays or accelerations in work may necessitate changes to the planned timeline, leading to updates through a change order.

Thus, change orders are flexible instruments that can adjust both the financial and temporal aspects of a construction contract, covering all bases outlined in the choices provided.