Pantone (tm) and its Pantone Matching System / PMS (tm) provide a set of standardized colors. Robison-Anton licenses many of these colors which means that they conform to Pantone's standards. This is important because projects with precise color requirements often use Pantone as the benchmark. Also, if two manufacturers reference the same Pantone number, you can be sure that there colors are indistinguishable.
This conversion chart has about 300 Pantone / Robison-Anton Rayon colors. Click CTRL + F to find a specific color