New in V4.1.1: printed or otherwise non-digital characters and symbols needed for use, and unlabelled operable parts that are not tactilely discernible, must contrast with their background, light on dark or dark on light; logos are excluded, and a Michelson contrast of 0.7 for characters and 0.4 for unlabelled controls is a common approach.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.