Yarn parameters or thread parameters are those properties of a yarn that are relevant to the crafter. They are specified in yarn exchange formats such as YarnML.
Yarn color is the most fundamental of yarn parameters. To allow for compatibility the color should be provided in relation to a standardized color space.
Each yarn is made up of a number of plies. While each ply is often made of the same material this is not be the case for so called effect yarns. For example Brother offers a series of fleshtone, metallic, and polyester threads, where specific surface effects are achieved by combining plies of different colours and materials. An open yarn standard should allow to specify a hierarchical structure of plies and their direction of twist.
In so called variegated threads the colour changes slowly alongside the thread. Variegated threads are used in ikat techniques, and can produce colourful results, with a limited number of thread bobbins. A standard representation of ikat threads, would require a continuous colour function, which can be specified by a number of key-frame colours and the distance between them.
While L*a*b colours may be sufficient to capture the colour of threads or plies, various other factors such as reflectivity and transparency might be considered part of extended colour information.