Basically it is just for when you have had a busy session and just want a little peace and quiet, load up each track with GND “-“ lay out your trigs and bliss out to some proper minimal 
Edit: Joking aside could be useful when switching kits for silencing certain tracks only?
MD’s GND “—” can be useful, not sure about MnM’s (apparently lfo’s per track, no mute groups, no CTR ALL?).
Gnd “---”
The only thing I can think of is if you need more channels to sequence MIDI… maybe if you have a sweet GM module and want to get 12 channels rockin’ 
Well it’s the tiniest of adds but none-the-less:
In the A4 manual appednix D: MIDI, page D-5, the CC number for the filter overdrive is 86.
I recently went back over the Octatrack’s Arranger, determined to learn the thing once and for all. I made a few notes where the documentation felt lacking, dunno if these are useful:
The manual’s description of looping could be improved if it simply told you that when a loop row is reached, it branches back to the specified row (default 000) and does so as many times as you specify (default infinity).
A useful pointer for the Arranger Editor would have been: Remember to move the cursor away from a field that opens a menu in order to hit enter and play from that point. So if you’re doing lots of mutes, you can’t simply move one step to the right but have to move left past mute, transpose and tempo.
There is only one tempo maintained throughout. Therefore, the sentence that says ‘if there is no setting, the tempo is the main BPM’ really means nothing. Any BPM that is set takes over and remains the main BPM even when you leave Arrange mode, regardless of what it was before.
Make sure tracks are unmuted before you start using the Arranger Editor or you’ll be well confused.
Within Arrange Edit, the changes you make to mutes don’t take effect until the next time the row is engaged.
Just those few things would have saved me a few furrowed brows, but I’m old and dim.
The tutorial should be corrected, and eventually the note list (invert active track up / down), eventually change terms, like previous, next, increment decrement…
Thanks 
I fixed that now on both A4 manuals. It will show up next time I update the PDF manuals.
Maybe a little mistake with NLEN?
10.6.4 LEG Controls the legato of the arpeggiator. This setting will affect the note trigs of the track even if the MOD setting is set to OFF. ON will play overlapping notes legato, releasing the old note after the new one. The NLEN setting adjusts the length of the notes when the arpeggiator is activated. If not activated the LEN setting will adjust the length of the notes. OFF will send out a MIDI note off message before the start of each arpeggiated note.
Hmmm not sure what is wrong there… Enlighten me.
I didn’t precise, A4 MKI. I can’t see any NLEN.
Only Note LEN or Arp LEN.
There is a NLEN for Octatrack.
Ahh ok. Yes I had a look at it and corrected this for both AF MKI and MKII. The text now reads:
“ON will play overlapping notes legato, releasing the old note after the new one. The LEN parameter adjusts the length of the notes when the arpeggiator is activated. If the arpeggiator is not activated, then the LEN parameter on the NOTE menu will adjust the length of the notes.”
Thanks for catching this
On p. 33 of the Digitone manual, 10.5 Voice Menu, the text says: “A dot next to the track number indicates that the sound is in mono. For more information, please see ‘9.5. Sound Setup Menu’ on page 26.”
Is that cross-reference correct? I don’t see anything related to mono sounds in section 9.5 or on p. 26.
Sorry if I’m missing something!
In addition, on p. 66 of the manual, near the bottom, some of the formatting of the text in the “Auto Channel” paragraph is messed up. The error appears in the sentence that reads “This function is useful when you want to change quickly between the active synth track to play different S20
ounds.”
Edit: Another minor one. On p. 44 of the manual, in the last paragraph on the page, after the second to last sentence, the following text appears: “J50 (-64-63).” I think it needs to be deleted.
CC NRPN for Mute missing in A4’s MKI manual
Can I automate the 4 synth tracks levels with midi CC?
Digitakt
8.4 MIDI NOTES
Some functions can be triggered by sending MIDI note values from an external MIDI device (a MIDI keyboard or a computer, for example) connected to the Digitakt via a standard MIDI cable or a USB 2.0 A to B connector cable. Of the 128 notes in the standard MIDI range, Note numbers 0–8 correspond to notes C0 through to G0
0-7 instead?
Finally had time to have a look at this. You are correct on all accounts and I have now fixed it in the manual. Thanks!
It is indeed. Fixed it in both AF MKI and AF MKII manuals. Thanks for the heads up!
Obviously, you can count to 8, unlike me I have fixed that in the manual now. Thanks!
AR2 gain reduction bar is still mentioned in the manual, but it has been disabled apparently.
Hmm… Im looking at the AR MKII User Manual on the website. Here this text is corrected. Am I missing something?
There were at least two previous versions of the 1.45 manual that were issued in July 2018 before you deleted the reference to the gain reduction bar in the current (January 2019) version.