SABLE is pretty advanced. It is a "XML-based [language that] allows users to add addition controlling commands in text to affect the output." https://www.cs.cm

SABLE is pretty advanced. It is a "XML-based [language that] allows users to add addition controlling commands in text to affect the output." https://www.cs.cmu.edu/~awb/festival_demos/sable.html https://www.cs.cmu.edu/~awb/festival_demos/sable.html It's part of the Festival TTS system.