What is referred to as a face or edge from where all the measurements are taken?

The term that describes a face or edge from which all measurements are taken is a datum. A datum serves as a fundamental starting point for measurements on a part or assembly, ensuring that all features are referenced accurately and consistently. In engineering and manufacturing, establishing a datum is crucial for precision, as it helps to eliminate ambiguity about how dimensions are noted and how parts will fit together.

In practical applications, a datum can be a physical feature of the component, such as a flat surface, an edge, or a cylindrical point that can be easily identified. This sets a standard reference that machinists and engineers use during the design and manufacturing processes, promoting accuracy and interoperability of components.

While the other options might seem related, they refer to different concepts. A reference point is a general term that can refer to any point used for measurement but does not necessarily imply the standardization that a datum provides. A coordinate typically refers to a specific numerical value or location within a defined grid or system, while a benchmark is generally used as a point of reference for elevation or quality rather than a physical edge or face from which measurements start.