C diminished (whole–half)

C1D2E♭♭3F4G♭♭5A♭♭6A6B7

Eight notes alternating whole step and half step. Symmetrical, so it repeats every minor third.

Written out

Fig. 2 · C diminished (whole–half), ascending

Every accidental is written in, rather than left to a key signature, so the letters can be read one at a time.

CWDHE♭WFHG♭WA♭HAWBHC

C diminished (whole–half) is C, D, E♭, F, G♭, A♭, A and B, and back to C.

Its steps are W – H – W – H – W – H – W – H, where W is a whole step and H a half.

Found by testing every chord in the catalogue against these 8 sounds, not chosen.