The ISO gray scale evaluates color gradation and color change

Grey scale for change in color ISO 105 A02
The gray scale consists of nine pairs of neutral grays without shadows, representing color differences. These ratings give 5, 4-5, 4, 3-4, 3, 2-3, 2, 1-2 and 1 endurance levels, respectively.

They are used in the assessment of color changes occurring in fastness tests as described in ISO 105-A02. And often used with color matching cabinets..

Grey scale for staning ISO 105 A03
The gray scale consists of nine pairs of gray and white without shadows, illustrating the perceived depth of color. These give a durability level of 5, 4-5, 4, 3-4, 3, 2-3, 2, 1-2, 1 respectively.

They are used to evaluate the amount of staining that occurs on adjacent undyed fabrics during fastness tests. Their use is described in ISO 105-A03.

ISO 105 A03.