bVI–bVII–I

Two major chords from outside the key, each a whole tone above the last, and then the tonic: the reader looks for all three in a row, in that order, and marks the run as one move.

The rule, as the reader applies it

  1. In a key whose tonic chord is major: a major chord a minor sixth above the tonic, then a major chord a minor seventh above the tonic, then a major chord on the tonic.

Where it fires: two times in two lines

Every line in this site’s corpus where bVI–bVII–I fires: the line, the key it is read in, the chords the move covers and their numerals.
Line Read in Chords Numerals Line from
C Bb Ab Bb C C mixolydian Ab Bb C bVI–bVII–I as printed in Borrowed chord, “Common borrowed chords” (Wikipedia)
Ab Bb C C mixolydian Ab Bb C bVI–bVII–I as printed in The Flat VI-Flat VII-I Cadence (StudyBass)

The move as declared here was read from The Flat VI-Flat VII-I Cadence (StudyBass), which prints it as bVI–bVII–I in C major: Ab–Bb–C.

Spotting it

This is the one move the reader finds across three chords. It looks for a major chord a minor sixth above the tonic, then a major chord a minor seventh above it, then the major tonic chord itself, in that order and with nothing in between, in a key whose tonic chord is major. The label sits on the first of the three chords and the span covers all of them. In C the run is Ab, Bb and C.

In the table

The three numerals read bVI, bVII and I. Ab Bb C is the whole run on its own, as the source prints it; C Bb Ab Bb C reaches it after a turn through the same two chords in the other direction, and fires it on its last three. Both lines read in C mixolydian, where the Bb belongs to the key and only the Ab chord has notes outside it, so its row also carries the flat six. The run rule does not ask whether any chord is outside the key, only for the three roots and qualities in order.

Because the run is one move, its chip appears once, on the first of the three rows, and the firing table's span covers all three chords. A line that climbs the same way twice gets one label per climb; the reader never merges two runs into one.

What is not flagged

The order is the move. Ab C Bb C holds all three chords but not as a run, and nothing about the three-chord move fires. A minor tonic does not count either: Cm Ab Bb Cm climbs through the same roots to C minor, and in that key the bVI and bVII are its own chords and the rule, which asks for a major tonic chord, stays silent.