What is "precisely specify value by product" central to?

“Precisely specify value by product” is central to Lean thinking. Lean thinking is a philosophy and a set of principles and practices that aim to eliminate waste and optimize value delivery. Value is defined as anything that a customer is willing to pay for or that meets their needs or desires. Value is specified by product, which means that each product or service should have a clear and explicit definition of what value it provides to the customer and how it differs from other products or services. Specifying value by product helps avoid ambiguity, confusion, and inefficiency in the value delivery process. References: Thriving in the Digital Age, SAFe Principle #1