Timing mark

[1] These have the largest radius rotating at crankshaft speed and therefore are the place where marks at one degree intervals will be farthest apart.

[2] Shining the light on the timing marks makes them appear stationary due to the stroboscopic effect.

The timing can be adjusted by loosening and slightly rotating the distributor in its seat.

See, for example, U.S. Patent 3,218,439 (filed 1964, granted 1965), which refers to a timing track down the left side of the form, and U.S. Patent 3,267,258 (filed 1963, granted 1966), which refers to a column of timing marks on the right side of the form.

The term can also be used to describe the timing patterns used in some barcodes, such as PostBar, Data Matrix, Aztec Code, etc.