Mixing : Automation : Automation Modes : Latch Mode

Latch Mode
Latch mode works in the same way as Touch mode, writing automation only if you touch or move a control. However, unlike Touch, writing of automation continues until you stop playback or “punch out” of the automation pass by changing the Automation mode to Read or Touch.
AutoMatch can be applied to a Latch automation pass. See AutoMatch Time.
Latch mode is particularly useful for automating Pan controls and plug-ins on non-touch sensitive rotary controls, since it does not time out and revert to its previous position when you release a control.