A combination waveform is

a waveform output by a combination waveform generator circuit.

There are mainly 1.2/50μs combination (1.2/50μs voltage surge, 8/20μs current surge) applied to power lines,

and 10/700μs combination waveform (10/700μs voltage surge, 5/320μs current surge) applied to communication lines.

A combination generator circuit is

a circuit that realizes both voltage and current surge outputs with a single circuit.

It is a circuit that outputs a voltage surge of the specified waveform when the output terminal is in an open circuit state,

and outputs a current surge of the specified waveform when the output terminal is in a short circuit state.