Directions — plain language in square brackets before a line: [breathless] I can't believe it. Sounds & pauses — bracketed where they happen: [sigh][laugh][pause] Paired tags — wrap specific words: <whisper>Go on without me.</whisper><emphasis>Now.</emphasis><slow>...</slow><fast>...</fast> Multi-speaker — not supported in this simple UI; use the API directly with <|speaker:0|> tags.