Instructions rely on ability to see
Instructions for an element MUST NOT rely solely on references to sensory characteristics.
When instructions to use content rely on a person's ability to see things such as shape, size, visual location, or orientation, people who are blind or have low vision are at a risk of being unable to understand the information or follow the instructions. Instructions may include such visual cues as long as the information is conveyed in other ways as well, for example in text. Providing additional information other than shape, color, size, location, or orientation will allow people who are blind or have low vision to understand the instructions.
Fix this issue by ensuring that instructions that refer to shape, color, size, position, or orientation also reference another non-visual characteristic - such as a text label - that can be accessed using assistive technology - such as a screen reader - and by people who cannot perceive color.