What type of purchase is characterized by a buyer changing terms or specifications on a repeat order?

The correct answer is modified rebuy. This type of purchase occurs when a buyer seeks to make changes to their previous order, such as adjusting terms, specifications, or quantities, while still maintaining a relationship with the supplier. This situation often arises when the buyer finds that their needs have evolved or when they want to improve upon past orders without starting from scratch.

Modified rebuy is particularly relevant in business contexts where established suppliers can provide the flexibility necessary for adjustments based on evolving requirements, such as updated technology or shifting market conditions. It allows for a balance of reliability from the existing supplier and responsiveness to the changing needs of the buyer.

In contrast, a straight rebuy involves the buyer ordering the same products under the same terms without any modifications, while a new purchase indicates a completely new product or supplier relationship being initiated. The term "irregular purchase" is not a standard categorization in this context and does not accurately reflect the process of altering existing orders.