This document specifies a procedure, including computation, for extending the method described in ISO 18619:2015 to n-colour ICC profiles specifically for the xCLR cases where the colourants are either CMYK plus combinations from the set of red, orange, green, blue and violet or where, for the 3CLR case, the colourants are CMY-like chromatic colourants with widely-spaced hue angles. Other types of colour spaces which are otherwise permitted by 15076-1, such as 2CLR (two-device colourants), are not addressed by this document.