A time gap between the shot-instant and the start of recording by a seismograph to avoid long, blank sections on a record. It is used particularly in reflection work over deep water where there is no geologic reason to record while the energy is travelling through the water column, and the recording starts just before the expected first arrival. It is also used in time-domain induced polarization surveying to allow for the dissipation of transient voltages which have no direct relation to the over-voltage.