You may wish to test parallelism of the following : [substeps] Planar surface: opposite flat surfaces of a rectangular solid need to be parallel to each other. Cylindrical surface: a cylinder appears round when looking at its end, but when held upright, its sides must be parallel for the cylinder to function properly.
[header] How to measure parallelism [title] Define the surface for testing. [step] Parallelism is a quality that can be tested on several different types of surfaces. These are labeled based on their positions relative to each other.