What is the name of the line used to keep masonry units aligned from corner to corner?

The line used to keep masonry units aligned from corner to corner is known as the mason's line. This line is crucial in masonry work as it helps ensure that the blocks or bricks are laid straight and level. It serves as a visual guide for bricklayers and masons, allowing them to maintain consistent alignment across the structure, which is vital for both structural integrity and aesthetic appeal.

Using a mason's line, masons can check the alignment of their work as they progress, minimizing errors and ensuring that the wall or structure is built correctly from the start. This technique is fundamental in masonry to establish straight edges and can greatly enhance the overall quality of the project. Other terms like level line, reference line, and guide line may refer to different tools or concepts in construction but do not specifically refer to the function of aligning masonry units as effectively as a mason's line.