What term is used for letters and numbers that help locate particular points on a blueprint?

The term "zone numbers" is used to identify specific areas or sections on a blueprint, facilitating the organization and navigation of the overall design. These numbers help anyone reading the blueprint to quickly reference different parts of the plan, ensuring clear communication and efficiency in the construction or design process. Zone numbers are especially beneficial in complex designs where multiple sections need to be referenced or explained distinctly.

In the context of blueprints, other terms do exist, but they have different applications. For instance, coordinate numbers typically refer to numerical systems used in mathematical graphs or mapping, rather than architectural plans. Reference codes might suggest a system of identifying parts of a plan but do not specifically imply a locational aspect. Index points, while they might suggest connections on a grid, are not as commonly used or recognized in architectural terminology as zone numbers. Hence, zone numbers serve as an important and commonly understood method of referencing specific locations on blueprints.