 Scale-step

In Schenkerian theory, a scale-step () is a triad (based on one of the diatonic scale degrees) that is perceived as an organizing force for a passage of music (in accordance with the principle of composing-out).In "Harmony", Schenker gives the following example and asserts that 
A scale-step triad is designated by an uppercase Roman numeral representing the scale degree of the root, much as in traditional "harmonic analysis" (see chord progression).