Three note groups of the diatonic scale in the chromatic circle. Because the diatonic scale possesses a quality known as "cardinality equals variety" given a consecutive three note group, such as CDE, there are three classes of three note groups in the diatonic scale : MM/22 (red), Mm/21 (yellow), and mM/12 (blue).
<a href="//commons.wikimedia.org/wiki/User:Hyacinth" title="User:Hyacinth">Hyacinth</a>
<span class="int-own-work" lang="en">Own work</span>