Optionalcontentidentity of the content behind a synthesised track, id@version#sha256, so a save replays the same bytes or says it cannot
Optionalenginethe engine that voiced it ('retro:mt32'), so a restore picks the same one when it can
Optionalframeplayhead in source frames, exact where pos in seconds is not; a restore skips to it
OptionalpanOptionalpitchOptionalposOptionalpriorityfor playSe only: asks the shared SfxArbiter for a voice at this priority; 0 when omitted
Optionalvolume
A named track request in role-playing units: volume 0 to 100, pitch 50 to 150 percent, pan -100 to 100, an optional resume position in seconds.