The trigger/gate represents synchronization devices like for example the digital trigger and/or gate generators. Their main role is to synchronize acquisition of the experimental channels.
Trigger or gate characteristics could be described in either the time and/or the position configuration domains.
In the time domain, elements are configured in time units (seconds) and generation of the synchronization signals is based on passing time.
The concept of position domain is based on the relation between the trigger/gate and the moveable element. In the position domain, elements are configured in distance units of the moveable element configured as the feedback source (this could be mm, mrad, degrees, etc.). In this case generation of the synchronization signals is based on receiving updates from the source.