Output signal to a bus, the sample offset within the bus is kept exactly; i.e. if the synth is scheduled to be started part way through a control cycle, OffsetOut will maintain the correct offset by buffering the output and delaying it until the exact time that the synth was scheduled for.
For achieving subsample accuracy see SubsampleOffset
The index of the bus to write out to. The lowest numbers are written to the audio hardware.
An Array of channels or single output to write out. You cannot change the size of this once a SynthDef has been built.