Ardour has automation modes for many of it's controls. As of version 5.9, OSC can control what automation mode a fader uses. (See Automation.)
The form of the automation mode command is:
/strip/[control]/automation ii ssid mode
0
Manual mode1
Play mode2
Write mode3
Touch mode
The next version of Ardour will add /strip/[control]/automation_name is ssid mode_name
as feedback. A surface may choose to use only the first character of the string (M, P, W or T) instead of
the whole string (this is in git now).