Johannus SWEELINCK 17 User Manual page 31

Sys ex code stops (Program Changes)
When a MIDI stop is switched on and off, besides the usual Program
Change, an extra Program Change code (preceded by the sys ex code 3F)
is transmitted through the MIDI SEQ. output. This is to distiguish between a
'normal' organ stop and a MIDI stop before transmitting a module.
When a stop is switched on and off, the following codes are transmitted:
/i
Organ stop: Through MIDI SEQ. : CB XX
MIDI stop: Through MIDI MOD. : CX XX
Through MIDI SEQ. : CB XX and 3F CX XX
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