Universal Stylus Initiative
The Universal Stylus Initiative (USI) is a non-profit alliance of companies promoting a technical standard for interoperable active pen styluses on touchscreen devices such as phones, tablets, and computers. It defines a two-way communication protocol between the stylus and the computer and allows the stylus to remember user preferences for ink color and stroke.
Source: Wikipedia — Universal Stylus Initiative (CC BY-SA 4.0)