Short octave
From Inspired Acoustics Knowledge Base
A short octave in pipe organs refers to a group of keys on the keyboard or the pedal board with less keys than an octave and sometimes with different key responses than what is usual. For example a short octave of the 1778 Pazicky baroque organ of the R. C. St. Imre church in Pusztaszabolcs has a short lower octave with keys starting from E, but with a mapping starting at C, so the E key plays a C note.
