The settings on the Burst tab are only available if the Mute checkbox is NOT selected.

On (ms)  - The noise duration in milliseconds used to make up the toneburst.  Only available if the waveform is noise.

Cycles  - The number of cycles of Frequency 1 (Hz) used to make up the toneburst.  Only available if the waveform is NOT noise.

Period (ms) - the duration in milliseconds of each toneburst.

Fire - fires a single toneburst.  Not available if Mute is cleared so there is currently tone output.

Auto - tonebursts are fired continuously.  Not available if Mute is cleared so there is currently tone output.