Cool feature I didn’t know :
When Arp is activated, if note LENgth = 0, it plays a chord. 
Exemple here, just 1 bar midi track with arp, TRC, random lfos on LEN and arp NLEN, VEL
Playing Micromonsta (monotimbral 8 voices synth), just tweaking its filter.
The idea is to play bass, chords, lead on 1 midi track.
Didn’t see it the manual. Is it well known ?
LEN sets the duration of the notes. When a note has finished playing a NOTE OFF command will be sent. A max setting equals infinite note length. This setting also controls the length of an arpeggio. When the set time has elapsed the arpeggio will be cut off.
After reflexion, from above it is logical if it’s deactivated with LEN with 0 value, as the set time is already elapsed. 
I was using Arp mode plock / lfo before, this LEN behavior is interesting too.