The full-tone color patches at the beginning and end of each row are control patches. They are used to check whether the measurements will be done in the right order and direction. They also help identify the current row number. The first row always starts with a black patch and is followed by a white patch.

The colors of the control patches are different from chart to chart. Depending on the defined color model (e.g. CMYK, n-color, etc.) two full-tone colors with maximum deltaE will be used.